AD ADUC836BSZ

MicroConverter ®, Dual 16-Bit -
ADCs with Embedded 62 kB Flash MCU
ADuC836
FEATURES
High Resolution - ADCs
2 Independent ADCs (16-Bit Resolution)
16-Bit No Missing Codes, Primary ADC
16-Bit rms (16-Bit p-p) Effective Resolution @ 20 Hz
Offset Drift 10 nV/C, Gain Drift 0.5 ppm/C
Memory
62 Kbytes On-Chip Flash/EE Program Memory
4 Kbytes On-Chip Flash/EE Data Memory
Flash/EE, 100 Year Retention, 100 Kcycles Endurance
3 Levels of Flash/EE Program Memory Security
In-Circuit Serial Download (No External Hardware)
High Speed User Download (5 Seconds)
2304 Bytes On-Chip Data RAM
8051 Based Core
8051 Compatible Instruction Set
32 kHz External Crystal
On-Chip Programmable PLL (12.58 MHz Max)
3  16-Bit Timer/Counter
26 Programmable I/O Lines
11 Interrupt Sources, 2 Priority Levels
Dual Data Pointer, Extended 11-Bit Stack Pointer
On-Chip Peripherals
Internal Power on Reset Circuit
12-Bit Voltage Output DAC
Dual 16-Bit - DACs/PWMs
On-Chip Temperature Sensor
Dual Excitation Current Sources
Time Interval Counter (Wake-Up/RTC Timer)
UART, SPI®, and I2 C® Serial I/O
High Speed Baud Rate Generator (Including 115,200)
Watchdog Timer (WDT)
Power Supply Monitor (PSM)
Power
Normal: 2.3 mA Max @ 3.6 V (Core CLK = 1.57 MHz)
Power-Down: 20 A Max with Wake-Up Timer Running
Specified for 3 V and 5 V Operation
Package and Temperature Range
52-Lead MQFP (14 mm  14 mm), –40C to +125C
56-Lead LFCSP (8 mm  8 mm), –40C to +85C
APPLICATIONS
Intelligent Sensors
Weigh Scales
Portable Instrumentation, Battery-Powered Systems
4–20 mA Transmitters
Data Logging
Precision System Monitoring
FUNCTIONAL BLOCK DIAGRAM
ADuC836
AVDD
AIN1
AIN2
AIN3
AIN4
BUF
MUX
PGA
PRIMARY
16-BIT - ADC
AGND
AUXILIARY
16-BIT - ADC
MUX
AIN5
REFIN–
EXTERNAL
VREF
DETECT
INTERNAL
BAND GAP
VREF
RESET
DVDD
12-BIT
DAC
DUAL
16-BIT
- DAC
BUF
IEXC1
IEXC2
DAC
PWM0
MUX
PWM1
8051-BASED MCU WITH ADDITIONAL
PERIPHERALS
62 KBYTES FLASH/EE PROGRAM MEMORY
4 KBYTES FLASH/EE DATA MEMORY
2304 BYTES USER RAM
POR
DGND
CURRENT
SOURCE
DUAL
16-BIT
PWM
TEMP
SENSOR
REFIN+
AVDD
PLL AND PROG
CLOCK DIV
OSC
WAKE- UP/
RTC TIMER
3  16 BIT TIMERS
BAUD R ATE TIMER
POWER SUPPLY MON
WATCHDOG TIMER
4  PARALLEL
PORTS
UART, SPI, AND I2C
SERIAL I/O
XTAL1 XTAL2
GENERAL DESCRIPTION
The ADuC836 is a complete smart transducer front end, integrating
two high resolution - ADCs, an 8-bit MCU, and program/data
Flash/EE memory on a single chip.
The two independent ADCs (primary and auxiliary) include a
temperature sensor and a PGA (allowing direct measurement
of low level signals). The ADCs with on-chip digital filtering and
programmable output data rates are intended for the measurement of wide dynamic range, low frequency signals, such as those
in weigh scale, strain gage, pressure transducer, or temperature
measurement applications.
The device operates from a 32 kHz crystal with an on-chip PLL
generating a high frequency clock of 12.58 MHz. This clock is
routed through a programmable clock divider from which the MCU
core clock operating frequency is generated. The microcontroller
core is an 8052 and therefore 8051 instruction set compatible
with 12 core clock periods per machine cycle.
62 Kbytes of nonvolatile Flash/EE program memory, 4 Kbytes of
nonvolatile Flash/EE data memory, and 2304 bytes of data RAM
are provided on-chip. The program memory can be configured as
data memory to give up to 60 Kbytes of NV data memory in data
logging applications.
REV. A
On-chip factory firmware supports in-circuit serial download and
debug modes (via UART), as well as single-pin emulation mode
via the EA pin. The ADuC836 is supported by a QuickStart™
development system featuring low cost software and hardware
development tools.
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
that may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices.Trademarks and
registered trademarks are the property of their respective companies.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
www.analog.com
Fax: 781/326-8703
© 2003 Analog Devices, Inc. All rights reserved.
ADuC836
TABLE OF CONTENTS
FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
NONVOLATILE FLASH/EE MEMORY
Flash/EE Memory Overview . . . . . . . . . . . . . . . . . . . . . . . .29
Flash/EE Memory and the ADuC836 . . . . . . . . . . . . . . . . .29
ADuC836 Flash/EE Memory Reliability . . . . . . . . . . . . . . .29
Flash/EE Program Memory . . . . . . . . . . . . . . . . . . . . . . . .30
Serial Downloading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
Parallel Programming . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
User Download Mode (ULOAD) . . . . . . . . . . . . . . . . . . . .31
Flash/EE Program Memory Security . . . . . . . . . . . . . . . . . .31
Lock, Secure, and Serial Safe Modes . . . . . . . . . . . . . . . . . .31
Using the Flash/EE Data Memory . . . . . . . . . . . . . . . . . . .32
ECON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
Programming the Flash/EE Data Memory . . . . . . . . . . . . .33
Flash/EE Memory Timing . . . . . . . . . . . . . . . . . . . . . . . . . .33
APPLICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
FUNCTIONAL BLOCK DIAGRAM . . . . . . . . . . . . . . . . . .1
GENERAL DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . .1
SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
ABSOLUTE MAXIMUM RATINGS
. . . . . . . . . . . . . . . . .9
ORDERING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
PIN CONFIGURATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . .9
DETAILED BLOCK DIAGRAM . . . . . . . . . . . . . . . . . . . .10
PIN FUNCTION DESCRIPTIONS . . . . . . . . . . . . . . . . . .10
OTHER ON-CHIP PERIPHERALS
DAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34
PWM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36
On-Chip PLL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39
Time Interval Counter (Wake-Up/RTC Timer) . . . . . . . . .40
Watchdog Timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42
Power Supply Monitor . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
Serial Peripheral Interface (SPI) . . . . . . . . . . . . . . . . . . . . .44
I2C Serial Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46
Dual Data Pointer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48
MEMORY ORGANIZATION . . . . . . . . . . . . . . . . . . . . . . .13
SPECIAL FUNCTION REGISTERS (SFRS) . . . . . . . . . .14
Accumulator SFR (ACC) . . . . . . . . . . . . . . . . . . . . . . . . . .14
B SFR (B) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Data Pointer (DPTR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Stack Pointer (SP and SPH) . . . . . . . . . . . . . . . . . . . . . . . .15
Program Status Word (PSW) . . . . . . . . . . . . . . . . . . . . . . . .15
Power Control SFR (PCON) . . . . . . . . . . . . . . . . . . . . . . .15
ADuC836 Configuration SFR (CFG836) . . . . . . . . . . . . . .15
Complete SFR Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
8052 COMPATIBLE ON-CHIP PERIPHERALS
Parallel I/O Ports 0–3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49
Timers/Counters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52
UART Serial Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . .57
UART Operating Modes . . . . . . . . . . . . . . . . . . . . . . . . . . .57
Baud Rate Generation Using Timer 1 and Timer 2 . . . . . . .59
Baud Rate Generation Using Timer 3 . . . . . . . . . . . . . . . . .60
Interrupt System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61
ADC SFR INTERFACE
ADCSTAT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
ADCMODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
ADC0CON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
ADC1CON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
ADC0H/ADC0M/ADC1H/ADC1L . . . . . . . . . . . . . . . . . .20
OF0H/OF0M/OF1H/OF1L . . . . . . . . . . . . . . . . . . . . . . . .20
GN0H/GN0M/GN1H/GN1L . . . . . . . . . . . . . . . . . . . . . . .20
SF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
ICON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
HARDWARE DESIGN CONSIDERATIONS
External Memory Interface . . . . . . . . . . . . . . . . . . . . . . . . .63
Power Supplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64
Power-On Reset (POR) Operation . . . . . . . . . . . . . . . . . . .64
Power Consumption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64
Power Saving Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65
Wake-Up from Power-Down Latency . . . . . . . . . . . . . . . . .65
Grounding and Board Layout Recommendations . . . . . . . .66
ADuC836 System Self-Identification . . . . . . . . . . . . . . . . . .66
Clock Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66
PRIMARY AND AUXILIARY ADC NOISE
PERFORMANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
PRIMARY AND AUXILIARY ADC CIRCUIT
DESCRIPTION
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
Primary ADC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
Auxiliary ADC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Analog Input Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Primary and Auxiliary ADC Inputs . . . . . . . . . . . . . . . . . . .25
Analog Input Ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
Programmable Gain Amplifier . . . . . . . . . . . . . . . . . . . . . . .25
Bipolar/Unipolar Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . .25
Reference Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
Burnout Currents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
Excitation Currents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
Reference Detect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
- Modulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
Digital Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
ADC Chopping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
OTHER HARDWARE CONSIDERATIONS
In-Circuit Serial Download Access . . . . . . . . . . . . . . . . . . .67
Embedded Serial Port Debugger . . . . . . . . . . . . . . . . . . . . .67
Single-Pin Emulation Mode . . . . . . . . . . . . . . . . . . . . . . . .67
Typical System Configuration . . . . . . . . . . . . . . . . . . . . . . .68
QUICKSTART DEVELOPMENT SYSTEM . . . . . . . . . . .69
TIMING SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . .70
OUTLINE DIMENSIONS . . . . . . . . . . . . . . . . . . . . . . . . .80
–2–
REV. A
SPECIFICATIONS1
(AVDD = 2.7 V to 3.6 V or 4.75 V to 5.25 V, DVDD = 2.7 V to 3.6 V or 4.75 V to 5.25 V,
REFIN(+) = 2.5 V; REFIN(–) = AGND; AGND = DGND = 0 V; XTAL1/XTAL2 =
32.768 kHz Crystal; all specifications TMIN to TMAX, unless otherwise noted.)
Parameter
ADC SPECIFICATIONS
Conversion Rate
Primary ADC
No Missing Codes2
Resolution
Output Noise
Integral Nonlinearity
Offset Error3
Offset Error Drift
Full-Scale Error4
Gain Error Drift5
ADC Range Matching
Power Supply Rejection (PSR)
Common-Mode DC Rejection
On AIN
On REFIN
Common-Mode 50 Hz/60 Hz Rejection
On AIN
ADuC836
Test Conditions/Comments
Unit
5.4
105
On Both Channels
Programmable in 0.732 ms Increments
Hz min
Hz max
16
13.5
16
See Tables X and XI in
ADuC836 ADC Description
±15
±3
±10
±10
±0.5
±0.5
±2
95
80
20 Hz Update Rate
Range = ±20 mV, 20 Hz Update Rate
Range = ±2.56 V, 20 Hz Update Rate
Output Noise Varies with Selected
Update Rate and Gain Range
1 LSB
Bits min
Bits p-p typ
Bits p-p typ
95
113
125
At DC, AIN = 7.8 mV, Range = ±20 mV
At DC, AIN = 1 V, Range = ±2.56 V
At DC, AIN = 1 V, Range = ±2.56 V
20 Hz Update Rate
50 Hz/60 Hz ±1 Hz, AIN = 7.8 mV,
Range = ±20 mV
50 Hz/60 Hz ±1 Hz, AIN = 1 V,
Range = ±2.56 V
50 Hz/60 Hz ±1 Hz, AIN = 1 V,
Range = ±2.56 V
dBs typ
dBs typ
dBs typ
50 Hz/60 Hz ±1 Hz, 20 Hz Update Rate
50 Hz/60 Hz ±1 Hz, 20 Hz Update Rate
dBs typ
dBs typ
95
90
On REFIN
Normal Mode 50 Hz/60 Hz Rejection
On AIN
On REFIN
Auxiliary ADC
No Missing Codes2
Resolution
Output Noise
Integral Nonlinearity
Offset Error3
Offset Error Drift
Full-Scale Error6
Gain Error Drift5
Power Supply Rejection (PSR)
Normal Mode 50 Hz/60 Hz Rejection
On AIN
On REFIN
DAC PERFORMANCE
DC Specifications7
Resolution
Relative Accuracy
Differential Nonlinearity
Offset Error
Gain Error8
AC Specifications2, 7
Voltage Output Settling Time
Digital-to-Analog Glitch Energy
REV. A
ADuC836
90
60
60
16
16
See Table XII in ADuC836
ADC Description
±15
–2
1
–2.5
±0.5
80
60
60
12
±3
–1
±50
±1
±1
Range = ±20 mV to ±640 mV
Range = ±1.28 V to ±2.56 V
AIN = 18 mV
AIN = 7.8 mV, Range = ±20 mV
AIN = 1 V, Range = ±2.56 V
Range = ±2.5 V, 20 Hz Update Rate
Output Noise Varies with Selected
Update Rate
–3–
dBs typ
dBs typ
dBs typ
Bits min
Bits p-p typ
AIN = 1 V, 20 Hz Update Rate
ppm of FSR max
LSB typ
V/°C typ
LSB typ
ppm/°C typ
dBs typ
50 Hz/60 Hz ±1 Hz
50 Hz/60 Hz ±1 Hz, 20 Hz Update Rate
dBs typ
dBs typ
AVDD Range
VREF Range
Bits
LSB typ
LSB max
mV max
% max
% typ
Settling Time to 1 LSB of Final Value
1 LSB Change at Major Carry
s typ
nVs typ
Guaranteed 12-Bit Monotonic
15
10
ppm of FSR max
V typ
nV/°C typ
V typ
LSB typ
ppm/°C typ
V typ
dBs typ
dBs typ
ADuC836
SPECIFICATIONS (continued)
Parameter
INTERNAL REFERENCE
ADC Reference
Reference Voltage
Power Supply Rejection
Reference Tempco
DAC Reference
Reference Voltage
Power Supply Rejection
Reference Tempco
ADuC836
Test Conditions/Comments
Unit
1.25 ± 1%
45
100
Initial Tolerance @ 25°C, VDD = 5 V
V min/max
dBs typ
ppm/°C typ
2.5 ± 1%
50
±100
Initial Tolerance @ 25°C, VDD = 5 V
V min/max
dBs typ
ppm/°C typ
ANALOG INPUTS/REFERENCE INPUTS
Primary ADC
Differential Input Voltage Ranges9, 10
Bipolar Mode (ADC0CON3 = 0)
Analog Input Current2
Analog Input Current Drift
Absolute AIN Voltage Limits2
Auxiliary ADC
Input Voltage Range9, 10
Average Analog Input Current
Average Analog Input Current Drift2
Absolute AIN Voltage Limits2, 11
External Reference Inputs
REFIN(+) to REFIN(–) Range2
Average Reference Input Current
Average Reference Input Current Drift
“NO Ext. REF” Trigger Voltage
ADC SYSTEM CALIBRATION
Full-Scale Calibration Limit
Zero-Scale Calibration Limit
Input Span
ANALOG (DAC) OUTPUT
Voltage Range
Resistive Load
Capacitive Load
Output Impedance
ISINK
TEMPERATURE SENSOR
Accuracy
Thermal Impedance (JA)
External Reference Voltage = 2.5 V
RN2, RN1, RN0 of ADC0CON Set to
0 0 0 (Unipolar Mode 0 mV to 20 mV)
0 0 1 (Unipolar Mode 0 mV to 40 mV)
0 1 0 (Unipolar Mode 0 mV to 80 mV)
0 1 1 (Unipolar Mode 0 mV to 160 mV)
1 0 0 (Unipolar Mode 0 mV to 320 mV)
1 0 1 (Unipolar Mode 0 mV to 640 mV)
1 1 0 (Unipolar Mode 0 V to 1.28 V)
1 1 1 (Unipolar Mode 0 V to 2.56 V)
TMAX = 85°C
TMAX = 125°C
TMAX = 85°C
TMAX = 125°C
±20
±40
±80
±160
±320
±640
±1.28
±2.56
±1
±5
±5
±15
AGND + 100 mV
AVDD – 100 mV
0 to VREF
Unipolar Mode, for Bipolar Mode
See Note 11
Input Current Will Vary with Input
Voltage on the Unbuffered Auxiliary ADC
125
±2
AGND – 30 mV
AVDD + 30 mV
1
AVDD
1
±0.1
0.3
0.65
Both ADCs Enabled
NOXREF Bit Active if VREF < 0.3 V
NOXREF Bit Inactive if VREF > 0.65 V
1.05  FS
–1.05  FS
0.8  FS
2.1  FS
mV
mV
mV
mV
mV
mV
V
V
nA max
nA max
pA/°C typ
pA/°C typ
V min
V max
V
nA/V typ
pA/V/°C typ
V min
V max
V min
V max
A/V typ
nA/V/°C typ
V min
V max
V max
V min
V min
V max
0 to VREF
0 to AVDD
10
100
0.5
50
DACRN = 0 in DACCON SFR
DACRN = 1 in DACCON SFR
From DAC Output to AGND
From DAC Output to AGND
±2
90
52
MQFP Package
CSP Package (Base Floating)12
–4–
V typ
V typ
k typ
pF typ
 typ
A typ
°C typ
°C/W typ
°C/W typ
REV. A
ADuC836
Parameter
ADuC836
TRANSDUCER BURNOUT CURRENT SOURCES
AIN+ Current
–100
AIN– Current
+100
Initial Tolerance @ 25°C
Drift
±10
0.03
EXCITATION CURRENT SOURCES
Output Current
Initial Tolerance @ 25°C
Drift
Initial Current Matching @ 25°C
Drift Matching
Line Regulation (AVDD)
Load Regulation
Output Compliance2
LOGIC INPUTS
All Inputs Except SCLOCK, RESET,
and XTAL12
VINL, Input Low Voltage
VINH, Input High Voltage
SCLOCK and RESET Only
(Schmitt-Triggered Inputs)2
VT+
VT–
VT+ – VT–
Input Currents
Port 0, P1.2–P1.7, EA
SCLOCK, MOSI, MISO, SS13
RESET
P1.0, P1.1, Ports 2 and 3
Input Capacitance
Unit
AIN+ Is the Selected Positive Input
to the Primary ADC
AIN– Is the Selected Negative Input
to the Auxiliary ADC
nA typ
nA typ
% typ
%/°C typ
–200
±10
200
±1
20
1
0.1
AVDD – 0.6
AGND
Available from Each Current Source
0.8
0.4
2.0
DVDD = 5 V
DVDD = 3 V
V max
V max
V min
1.3/3
0.95/2.5
0.8/1.4
0.4/1.1
0.3/0.85
0.3/0.85
DVDD = 5 V
DVDD = 3 V
DVDD = 5 V
DVDD = 3 V
DVDD = 5 V
DVDD = 3 V
V min/V max
V min/V max
V min/V max
V min/V max
V min/V max
V min/V max
±10
–10 min, –40 max
±10
±10
35 min, 105 max
VIN = 0 V or VDD
VIN = 0 V, DVDD = 5 V, Internal Pull-Up
VIN = VDD, DVDD = 5 V
VIN = 0 V, DVDD = 5 V
VIN = VDD, DVDD = 5 V,
Internal Pull-Down
VIN = VDD, DVDD = 5 V
VIN = 2 V, DVDD = 5 V
A max
A min/A max
A max
A max
A min/A max
Matching between Both Current Sources
AVDD = 5 V + 5%
±10
–180
–660
–20
–75
5
VIN = 450 mV, DVDD = 5 V
All Digital Inputs
CRYSTAL OSCILLATOR (XTAL1 AND XTAL2)
Logic Inputs, XTAL1 Only2
VINL, Input Low Voltage
0.8
0.4
VINH, Input High Voltage
3.5
2.5
XTAL1 Input Capacitance
18
XTAL2 Output Capacitance
18
REV. A
Test Conditions/Comments
DVDD = 5 V
DVDD = 3 V
DVDD = 5 V
DVDD = 3 V
–5–
A typ
% typ
ppm/°C typ
% typ
ppm/°C typ
A/V typ
A/V typ
V max
V min
A max
A min
A max
A min
A max
pF typ
V max
V max
V min
V min
pF typ
pF typ
ADuC836
SPECIFICATIONS (continued)
Parameter
ADuC836
Test Conditions/Comments
Unit
VDD = 5 V, ISOURCE = 80 A
VDD = 3 V, ISOURCE = 20 A
ISINK = 8 mA, SCLOCK, MOSI/SDATA
ISINK = 10 mA, P1.0 and P1.1
ISINK = 1.6 mA, All Other Outputs
V min
V min
V max
V max
V max
A max
pF typ
2.63
4.63
±3.0
±4.0
2.63
4.63
±3.0
±4.0
Four Trip Points Selectable in This Range
Programmed via TPA1–0 in PSMCON
TMAX = 85°C
TMAX = 125°C
Four Trip Points Selectable in This Range
Programmed via TPD1–0 in PSMCON
TMAX = 85C
TMAX = 125C
V min
V max
% max
% max
V min
V max
% max
% max
0
2000
Nine Timeout Periods in This Range
Programmed via PRE3–0 in WDCON
ms min
ms max
98.3
Clock Rate Generated via On-Chip PLL
Programmable via CD2–0 Bits in
PLLCON SFR
kHz min
2
LOGIC OUTPUTS (Not Including XTAL2)
VOH, Output High Voltage
2.4
2.4
VOL, Output Low Voltage14
0.4
0.4
0.4
Floating State Leakage Current2
±10
Floating State Output Capacitance
5
POWER SUPPLY MONITOR (PSM)
AVDD Trip Point Selection Range
AVDD Power Supply Trip Point Accuracy
DVDD Trip Point Selection Range
DVDD Power Supply Trip Point Accuracy
WATCHDOG TIMER (WDT)
Timeout Period
MCU CORE CLOCK RATE
MCU Clock Rate2
START-UP TIME
At Power-On
After External RESET in Normal Mode
After WDT Reset in Normal Mode
From Idle Mode
From Power-Down Mode
Oscillator Running
Wake-Up with INT0 Interrupt
Wake-Up with SPI Interrupt
Wake-Up with TIC Interrupt
Wake-Up with External RESET
Oscillator Powered Down
Wake-Up with INT0 Interrupt
Wake-Up with SPI Interrupt
Wake-Up with External RESET
12.58
MHz max
300
3
3
10
ms typ
ms typ
ms typ
s typ
Controlled via WDCON SFR
OSC_PD Bit = 0 in PLLCON SFR
20
20
20
3
s typ
s typ
s typ
ms typ
OSC_PD Bit = 1 in PLLCON SFR
20
20
5
s typ
s typ
ms typ
FLASH/EE MEMORY RELIABILITY CHARACTERISTICS15
Endurance16
100,000
Data Retention17
100
Cycles min
Years min
–6–
REV. A
ADuC836
Parameter
POWER REQUIREMENTS
Power Supply Voltages
AVDD, 3 V Nominal Operation
AVDD, 5 V Nominal Operation
DVDD, 3 V Nominal Operation
DVDD, 5 V Nominal Operation
ADuC836
Test Conditions/Comments
2.7
3.6
4.75
5.25
2.7
3.6
4.75
5.25
V min
V max
V min
V max
V min
V max
V min
V max
5 V POWER CONSUMPTION
Power Supply Currents Normal Mode18, 19
DVDD Current
4
DVDD Current
13
16
AVDD Current
180
Power Supply Currents Power-Down Mode18, 19
DVDD Current
53
100
DVDD Current
30
80
AVDD Current
1
3
Typical Additional Power Supply Currents
(AIDD and DIDD)
PSM Peripheral
Primary ADC
Auxiliary ADC
DAC
Dual Current Sources
DVDD = 4.75 V to 5.25 V, AVDD = 5.25 V
Core CLK = 1.57 MHz
Core CLK = 12.58 MHz
Core CLK = 12.58 MHz
Core CLK = 1.57 MHz or 12.58 MHz
Core CLK = 1.57 MHz or 12.58 MHz
TMAX = 85°C; Osc. On, TIC On
TMAX = 125°C; Osc. On, TIC On
TMAX = 85°C; Osc. Off
TMAX = 125°C; Osc. Off
TMAX = 85°C; Osc. On or Osc. Off
TMAX = 125°C; Osc. On or Osc. Off
mA max
mA typ
mA max
A max
A max
A max
A max
A max
A max
A max
Core CLK = 1.57 MHz
50
1
500
150
400
A typ
mA typ
A typ
A typ
A typ
3 V POWER CONSUMPTION
Power Supply Currents Normal Mode18, 19
DVDD Current
2.3
DVDD Current
8
10
AVDD Current
180
DVDD = 2.7 V to 3.6 V
Core CLK = 1.57 MHz
Core CLK = 12.58 MHz
Core CLK = 12.58 MHz
AVDD = 5.25 V, Core CLK = 1.57 MHz
or 12.58 MHz
Core CLK = 1.57 MHz or 12.58 MHz
TMAX = 85°C; Osc. On, TIC On
TMAX = 125°C; Osc. On, TIC On
Osc. Off
AVDD = 5.25 V; TMAX = 85°C;
Osc. On or Osc. Off
AVDD = 5.25 V; TMAX = 125°C;
Osc. On or Osc. Off
Power Supply Currents Power-Down Mode18, 19
DVDD Current
20
40
DVDD Current
10
AVDD Current
1
3
REV. A
Unit
DVDD and AVDD Can Be Set Independently
–7–
mA max
mA typ
mA max
A max
A max
A max
A typ
A max
A max
ADuC836
NOTES
1
Temperature range for ADuC836BS (MQFP package) is –40°C to +125°C. Temperature range for ADuC836BCP (CSP package) is –40°C to +85°C.
2
These numbers are not production tested but are guaranteed by design and/or characterization data on production release.
3
System Zero-Scale Calibration can remove this error.
4
The primary ADC is factory calibrated at 25°C with AVDD = DVDD = 5 V yielding this full-scale error of 10 V. If user power supply or temperature conditions are significantly
different from these, an Internal Full-Scale Calibration will restore this error to 10 V. A system zero-scale and full-scale calibration will remove this error altogether.
5
Gain Error Drift is a span drift. To calculate Full-Scale Error Drift, add the Offset Error Drift to the Gain Error Drift times the full-scale input.
6
The auxiliary ADC is factory calibrated at 25°C with AVDD = DVDD = 5 V yielding this full-scale error of –2.5 LSB. A system zero-scale and full-scale calibration
will remove this error altogether.
7
DAC linearity and ac specifications are calculated using: reduced code range of 48 to 4095, 0 to VREF; reduced code range of 100 to 3950, 0 to VDD.
8
Gain Error is a measurement of the span error of the DAC.
9
In general terms, the bipolar input voltage range to the primary ADC is given by RangeADC = ±(VREF 2RN)/125, where:
VREF = REFIN(+) to REFIN(–) voltage and VREF = 1.25 V when internal ADC VREF is selected. RN = decimal equivalent of RN2, RN1, RN0, e.g.,
VREF = 2.5 V and RN2, RN1, RN0 = 1, 1, 0 the RangeADC = ±1.28 V. In Unipolar mode, the effective range is 0 V to 1.28 V in our example.
10
1.25 V is used as the reference voltage to the auxiliary ADC when internal VREF is selected via XREF0 and XREF1 bits in ADC0CON and ADC1CON, respectively.
11
In Bipolar mode, the auxiliary ADC can only be driven to a minimum of AGND – 30 mV as indicated by the auxiliary ADC absolute AIN voltage limits. The bipolar
range is still –VREF to +VREF; however, the negative voltage is limited to –30 mV.
12
The ADuC836BCP (CSP package) has been qualified and tested with the base of the CSP package floating.
13
Pins configured in SPI mode, pins configured as digital inputs during this test.
14
Pins configured in I2C mode only.
15
Flash/EE Memory Reliability Characteristics apply to both the Flash/EE program memory and Flash/EE data memory.
16
Endurance is qualified to 100 Kcycles as per JEDEC Std. 22 method A117 and measured at –40°C, +25°C, +85°C, and +125°C. Typical endurance at 25°C is 700 Kcycles.
17
Retention lifetime equivalent at junction temperature (TJ) = 55°C as per JEDEC Std. 22, Method A117. Retention lifetime based on an activation energy of 0.6 eV will
derate with junction temperature as shown in Figure 16 in the Flash/EE Memory section.
18
Power Supply current consumption is measured in Normal, Idle, and Power-Down modes under the following conditions:
Normal mode: Reset = 0.4 V, Digital I/O pins = open circuit, Core Clk changed via CD bits in PLLCON, Core Executing internal software loop.
Idle mode: Reset = 0.4 V, Digital I/O pins = open circuit, Core Clk changed via CD bits in PLLCON, PCON.0 = 1, Core Execution suspended in idle mode.
Power-Down mode: Reset = 0.4 V, All P0 pins and P1.2–P1.7 pins = 0.4 V, all other digital I/O pins are open circuit, Core Clk changed via CD bits in PLLCON,
PCON.1 = 1, Core Execution suspended in Power-Down mode, OSC turned on or off via OSC_PD bit (PLLCON.7) in PLLCON SFR.
19
DVDD power supply current will increase typically by 3 mA (3 V operation) and 10 mA (5 V operation) during a Flash/EE memory program or erase cycle.
Specifications subject to change without notice.
–8–
REV. A
ADuC836
ABSOLUTE MAXIMUM RATINGS1
PIN CONFIGURATIONS
52-Lead MQFP
(TA= 25°C, unless otherwise noted.)
AVDD to AGND . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to +7 V
AVDD to DGND . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to +7 V
DVDD to AGND . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to +7 V
DVDD to DGND . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to +7 V
AGND to DGND2 . . . . . . . . . . . . . . . . . . . . . . –0.3 V to +0.3 V
AVDD to DVDD . . . . . . . . . . . . . . . . . . . . . . . . . . . . –2 V to +5 V
Analog Input Voltage to AGND3 . . . . . . –0.3 V to AVDD + 0.3 V
Reference Input Voltage to AGND . . . . –0.3 V to AVDD + 0.3 V
AIN/REFIN Current (Indefinite) . . . . . . . . . . . . . . . . . . 30 mA
Digital Input Voltage to DGND . . . . . . –0.3 V to DVDD + 0.3 V
Digital Output Voltage to DGND . . . . . –0.3 V to DVDD + 0.3 V
Operating Temperature Range . . . . . . . . . . . . –40°C to +125°C
Storage Temperature Range . . . . . . . . . . . . . . –65°C to +150°C
Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . 150°C
JA Thermal Impedance (MQFP) . . . . . . . . . . . . . . . . . 90°C/W
JA Thermal Impedance (LFCSP Base Floating) . . . . . . 52°C/W
Lead Temperature, Soldering
Vapor Phase (60 sec) . . . . . . . . . . . . . . . . . . . . . . . . . . 215°C
Infrared (15 sec) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220°C
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NOTES
1
Stresses above those listed under Absolute Maximum Ratings may cause permanent
damage to the device. This is a stress rating only; functional operation of the device
at these or any other conditions above those listed in the operational sections of this
specification is not implied. Exposure to absolute maximum rating conditions for
extended periods may affect device reliability.
2
AGND and DGND are shorted internally on the ADuC836.
3
Applies to P1.2 to P1.7 pins operating in analog or digital input modes.
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ORDERING GUIDE
Model
Temperature Range
Package Description
Package Option
ADuC836BS
ADuC836BCP
EVAL-ADuC836QS
–40°C to +125°C
–40°C to +85°C
52-Lead Metric Quad Flat Package
56-Lead Lead Frame Chip Scale Package
QuickStart Development System
S-52
CP-56
CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate
on the human body and test equipment and can discharge without detection. Although the ADuC836
features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high
energy electrostatic discharges.Therefore, proper ESD precautions are recommended to avoid performance
degradation or loss of functionality.
REV. A
–9–
ADuC836
AIN1
BUF
AIN
MUX
AIN2
AIN3
AIN5
TEMP
SENSOR
PGA
BAND GAP
REFERENCE
REFIN
ADC CONTROL
AND
CALIBRATION
19
MCU
CORE
DUAL
16-BIT
PWM
DGND
RESET
SINGLE-PIN
EMULATOR
40 42
26
27
14
13
32
33
XTAL1
DVDD
41
XTAL2
AGND
17
SS
AVDD
16
DAC
1
PWM0
2
PWM1
22
T0
23
T1
1
T2
2
T2EX
18
INT0
19
INT1
OSC
MISO
15
SPI/I2C SERIAL
INTERFACE
MOSI/SDATA
47 21 35
WAKE-UP/
RTC TIMER
SCLOCK
20 34 48
16-BIT
COUNTER
TIMERS
PLL WITH PROG.
CLOCK DIVIDER
UART
TIMER
3
MUX
ALE
6
BUF
EA
5
TXD
UART
SERIAL PORT
POR
25
PSEN
CURRENT
SOURCE
MUX
24
POWER SUPPLY
MONITOR
200A
RXD
IEXC 1
23
DUAL
16-BIT
- DAC
DOWNLOADER
DEBUGGER
IEXC 2
22
12-BIT
VOLTAGE
OUTPUT DAC
WATCHDOG
TIMER
8052
P3.6 (WR)
18
2304 BYTES
USER RAM
4 KBYTES DATA
FLASH/EE
2  DATA POINTERS
11-BIT STACK POINTER
200A
17
PWM
CONTROL
62 KBYTES PROGRAM/
FLASH/EE
VREF
DETECT
REFIN
ADC
CONTROL
AND
CALIBRATION
PRIMARY ADC
16-BIT
- ADC
AUXILIARY ADC
16-BIT
- ADC
AIN
MUX
AIN4
DAC
CONTROL
16
P3.7 (RD)
39
P3.4 (T0/PWMCLK)
38
P3.5 (T1)
37
P3.3 (INT1)
36
P3.2 (INT0)
31
P3.0 (RXD)
30
P3.1 (TXD)
29
P2.7 (A15/A23)
28
P2.6 (A14/A22)
12
P2.5 (A13/A21)
11
P2.3 (A11/A19)
10
P2.4 (A12/A20)
9
P2.2 (A10/A18)
4
P2.0 (A8/A16)
3
P2.1 (A9/A17)
2
P1.7 (AIN4/DAC)
1
P1.6 (AIN3)
52
P1.4 (AIN1)
51
P1.5 (AIN2)
50
P1.3 (AIN5/IEXC 2)
P0.7 (AD7)
49
P1.2 (DAC/IEXC 1)
P0.6 (AD6)
46
P1.0 (T2)
P0.5 (AD5)
45
P1.1 (T2EX)
P0.4 (AD4)
44
P0.2 (AD2)
43
P0.3 (AD3)
P0.0 (AD0)
P0.1 (AD1)
ADuC836
*PIN NUMBERS REFER TO THE 52-LEAD MQFP PACKAGE
SHADED AREAS REPRESENT THE NEW FEATURES OF THE ADuC836 OVER THE ADuC816
Figure 1. Detailed Block Diagram
PIN FUNCTION DESCRIPTIONS
Pin No. Pin No.
52-Lead 56-Lead
MQFP CSP
Mnemonic
Type* Description
1, 2
P1.0/P1.1
I/O
P1.0/T2/PWM0
I/O
56, 1
P1.1/T2EX/PWM1 I/O
3–4,
9–12
2–3,
11–14
P1.2–P1.7
I
P1.2/DAC/IEXC1 I/O
P1.3/AIN5/IEXC2 I/O
P1.0 and P1.1 can function as digital inputs or digital outputs and have a pull-up
configuration as described for Port 3. P1.0 and P1.1 have an increased current drive
sink capability of 10 mA.
P1.0 and P1.1 also have various secondary functions as described below. P1.0 can be
used to provide a clock input to Timer 2. When enabled, Counter 2 is incremented
in response to a negative transition on the T2 input pin. If the PWM is enabled, the
PWM0 output will appear at this pin.
P1.1 can also be used to provide a control input to Timer 2. When enabled, a PWM1
negative transition on the T2EX input pin will cause a Timer 2 capture or reload event.
If the PWM is enabled, the PWM1 output will appear at this pin.
Port 1.2 to Port 1.7 have no digital output driver; they can function as a digital input
for which 0 must be written to the port bit. As a digital input, these pins must be
driven high or low externally. These pins also have the following analog functionality:
The voltage output from the DAC or one or both current sources (200 µA or
2  200 µA) can be configured to appear at this pin.
Auxiliary ADC input or one or both current sources can be configured at this pin.
–10–
REV. A
ADuC836
PIN FUNCTION DESCRIPTIONS (continued)
Pin No. Pin No.
52-Lead 56-Lead
MQFP CSP
Mnemonic
Type* Description
P1.4/AIN1
P1.5/AIN2
P1.6/AIN3
P1.7/AIN4/DAC
I
I
I
I/O
Primary ADC, Positive Analog Input
Primary ADC, Negative Analog Input
Auxiliary ADC Input or Muxed Primary ADC, Positive Analog Input
Auxiliary ADC Input or Muxed Primary ADC, Negative Analog Input. The voltage
output from the DAC can also be configured to appear at this pin.
5
4, 5
AVDD
S
Analog Supply Voltage, 3 V or 5 V
6
6, 7, 8
AGND
S
Analog Ground. Ground reference pin for the analog circuitry.
7
9
REFIN(–)
I
Reference Input, Negative Terminal
8
10
REFIN(+)
I
Reference Input, Positive Terminal
13
15
SS
I
Slave Select Input for the SPI Interface. A weak pull-up is present on this pin.
14
16
MISO
I/O
Master Input/Slave Output for the SPI Interface. A weak pull-up is present on this input pin.
15
17
RESET
I
Reset Input. A high level on this pin for 16 core clock cycles while the oscillator is
running resets the device. There is an internal weak pull-down and a Schmitt trigger
input stage on this pin.
16–19,
22–25
18–21,
24–27
P3.0–P3.7
I/O
P3.0/RXD
P3.1/TXD
P3.2/INT0
P3.3/INT1
P3.4/T0/PWMCLK
I/O
I/O
I/O
I/O
I/O
P3.5/T1
P3.6/WR
I/O
I/O
P3.7/RD
I/O
P3.0–P3.7 are bidirectional port pins with internal pull-up resistors. Port 3 pins that
have 1s written to them are pulled high by the internal pull-up resistors, and in that
state can be used as inputs. As inputs, Port 3 pins being pulled externally low will
source current because of the internal pull-up resistors. When driving a 0-to-1 output
transition, a strong pull-up is active for two core clock periods of the instruction
cycle. Port 3 pins also have various secondary functions including:
Receiver Data for UART Serial Port
Transmitter Data for UART Serial Port
External Interrupt 0. This pin can also be used as a gate control input to Timer 0.
External Interrupt 1. This pin can also be used as a gate control input to Timer 1.
Timer/Counter 0 External Input. If the PWM is enabled, an external clock may be
input at this pin.
Timer/Counter 1 External Input
External Data Memory Write Strobe. Latches the data byte from Port 0 into an
external data memory.
External Data Memory Read Strobe. Enables the data from an external data memory
to Port 0.
20, 34, 48 22, 36, 51, DVDD
S
Digital Supply, 3 V or 5 V
21, 35, 47 23, 37, 38, DGND
50
S
Digital Ground. Ground reference point for the digital circuitry.
26
SCLOCK
I/O
Serial Interface Clock for either the I2C or SPI Interface. As an input, this pin is a
Schmitt-triggered input, and a weak internal pull-up is present on this pin unless it is
outputting logic low. This pin can also be directly controlled in software as a digital
output pin.
27
MOSI/SDATA
I/O
Serial Data I/O for the I2C Interface or Master Output/Slave Input for the
SPI Interface. A weak internal pull-up is present on this pin unless it is outputting
logic low. This pin can also be directly controlled in software as a digital output pin.
28–31
36–39
30–33
39–42
P2.0–P2.7
(A8–A15)
(A16–A23)
I/O
Port 2 is a bidirectional port with internal pull-up resistors. Port 2 pins that have 1s
written to them are pulled high by the internal pull-up resistors, and in that state can
be used as inputs. As inputs, Port 2 pins being pulled externally low will source current
because of the internal pull-up resistors.
Port 2 emits the high order address bytes during fetches from external program memory
and middle and high order address bytes during accesses to the 24-bit external data
memory space.
32
34
XTAL1
I
Input to the Crystal Oscillator Inverter
33
35
XTAL2
O
Output from the Crystal Oscillator Inverter. (See the Hardware Design Considerations
section for description.)
REV. A
–11–
ADuC836
PIN FUNCTION DESCRIPTIONS (continued)
Pin No. Pin No.
52-Lead 56-Lead
MQFP CSP
Mnemonic
Type* Description
40
43
EA
I/O
External Access Enable, Logic Input. When held high, this input enables the device to
fetch code from internal program memory locations 0000h to F7FFh. When held low,
this input enables the device to fetch all instructions from external program memory.
To determine the mode of code execution, i.e., internal or external, the EA pin is
sampled at the end of an external RESET assertion or as part of a device power cycle.
EA may also be used as an external emulation I/O pin, and therefore the voltage level
at this pin must not be changed during normal mode operation as it may cause an
emulation interrupt that will halt code execution.
41
44
PSEN
O
Program Store Enable, Logic Output. This output is a control signal that enables the
external program memory to the bus during external fetch operations. It is active every
six oscillator periods except during external data memory accesses. This pin remains
high during internal program execution. PSEN can also be used to enable Serial
Download mode when pulled low through a resistor at the end of an external RESET
assertion or as part of a device power cycle.
42
45
ALE
O
Address Latch Enable, Logic Output. This output is used to latch the low byte (and
page byte for 24-bit data address space accesses) of the address to external memory
during external code or data memory access cycles. It is activated every six oscillator
periods except during an external data memory access. It can be disabled by setting
the PCON.4 bit in the PCON SFR.
43–46
49–52
46–49
52–55
P0.0–P0.7
(AD0–AD3)
I/O
These pins are part of Port 0, which is an 8-bit, open-drain, bidirectional
I/O port. Port 0 pins that have 1s written to them float and in that state can be used
(AD4–AD7)as high impedance inputs. An external pull-up resistor will be required
on P0 outputs to force a valid logic high level externally. Port 0 is also the multiplexed
low order address and data bus during accesses to external program or data memory.
In this application, it uses strong internal pull-ups when emitting 1s.
*I = Input, O = Output, S = Supply.
–12–
REV. A
ADuC836
MEMORY ORGANIZATION
Reset initializes the stack pointer to location 07H. Any call or push
pre-increments the SP before loading the stack. Therefore, loading
the stack starts from location 08H, which is also the first register
(R0) of register bank 1. Thus, if one is going to use more than one
register bank, the stack pointer should be initialized to an area of
RAM not used for data storage.
The ADuC836 contains four different memory blocks:

62 Kbytes of On-Chip Flash/EE Program Memory

4 Kbytes of On-Chip Flash/EE Data Memory

256 bytes of General-Purpose RAM

2 Kbytes of Internal XRAM
7FH
(1) Flash/EE Program Memory
GENERAL-PURPOSE
AREA
The ADuC836 provides 62 Kbytes of Flash/EE program memory to run user code. The user can choose to run code from this
internal memory or run code from an external program memory.
30H
2FH
BANKS
SELECTED
VIA
BITS IN PSW
If the user applies power or resets the device while the EA pin is
pulled low externally, the part will execute code from the external
program space; otherwise, if EA is pulled high externally, the part
defaults to code execution from its internal 62 Kbytes of Flash/EE
program memory.
BIT-ADDRESSABLE
(BIT ADDRESSES)
20H
1FH
11
18H
17H
Unlike the ADuC816, where code execution can overflow from the
internal code space to external code space once the PC becomes
greater than 1FFFH, the ADuC836 does not support the rollover
from F7FFH in internal code space to F800H in external code
space. Instead, the 2048 bytes between F800H and FFFFH will
appear as NOP instructions to user code.
10
10H
0FH
01
FOUR BANKS OF EIGHT
REGISTERS
R0–R7
08H
07H
00
Permanently embedded firmware allows code to be serially downloaded to the 62 Kbytes of internal code space via the UART serial
port while the device is in-circuit. No external hardware is required.
RESET VALUE OF
STACK POINTER
00H
Figure 2. Lower 128 Bytes of Internal Data Memory
(4) Internal XRAM
56 Kbytes of the program memory can be reprogrammed during
runtime; thus the code space can be upgraded in the field using a
user defined protocol or it can be used as a data memory. This
is discussed in more detail in the Flash/EE Memory section.
(2) Flash/EE Data Memory
4 Kbytes of Flash/EE Data Memory are available to the user and
can be accessed indirectly via a group of registers mapped into the
Special Function Register (SFR) area. Access to the Flash/EE Data
memory is discussed in detail in the Flash/EE Memory section.
The ADuC836 contains 2 Kbytes of on-chip extended data memory. This memory, although on-chip, is accessed via the MOVX
instruction. The 2 Kbytes of internal XRAM are mapped into the
bottom 2 Kbytes of the external address space if the CFG836.0
bit is set. Otherwise, access to the external data memory will occur
just like a standard 8051.
Even with the CFG836.0 bit set, access to the external XRAM
will occur once the 24-bit DPTR is greater than 0007FFH.
(3) General-Purpose RAM
FFFFFFH
FFFFFFH
The general-purpose RAM is divided into two separate memories:
the upper and lower 128 bytes of RAM. The lower 128 bytes of
RAM can be accessed through direct or indirect addressing; the
upper 128 bytes of RAM can only be accessed through indirect
addressing as it shares the same address space as the SFR space,
which can only be accessed through direct addressing.
EXTERNAL
DATA
MEMORY
SPACE
(24-BIT
ADDRESS
SPACE)
The lower 128 bytes of internal data memory are mapped as shown
in Figure 2. The lowest 32 bytes are grouped into four banks of
eight registers addressed as R0 through R7. The next 16 bytes
(128 bits), locations 20H through 2FH above the register banks,
form a block of directly addressable bit locations at bit addresses
00H through 7FH. The stack can be located anywhere in the internal memory address space, and the stack depth can be expanded
up to 2048 bytes.
EXTERNAL
DATA
MEMORY
SPACE
(24-BIT
ADDRESS
SPACE)
000800H
0007FFH
000000H
000000H
CFG836.0 = 0
2 KBYTES
ON-CHIP
XRAM
CFG836.0 = 1
Figure 3. Internal and External XRAM
GENERAL NOTES PERTAINING TO THIS DATA SHEET
1. SET implies a Logic 1 state and CLEARED implies a Logic 0 state, unless
otherwise stated.
2. SET and CLEARED also imply that the bit is set or automatically cleared by
the ADuC836 hardware, unless otherwise stated.
3. User software should not write 1s to reserved or unimplemented bits as they
may be used in future products.
4. Any pin numbers used throughout this data sheet refer to the 52-lead MQFP
package, unless otherwise stated.
REV. A
–13–
ADuC836
SPECIAL FUNCTION REGISTERS (SFRS)
When accessing the internal XRAM, the P0 and P2 port pins, as
well as the RD and WR strobes, will not be output as per a standard 8051 MOVX instruction. This allows the user to use these
port pins as standard I/O.
The upper 1792 bytes of the internal XRAM can be configured
to be used as an extended 11-bit stack pointer. By default, the
stack will operate exactly like an 8052 in that it will roll over from
FFH to 00H in the general-purpose RAM. On the ADuC836
however, it is possible (by setting CFG836.7) to enable the 11-bit
extended stack pointer. In this case, the stack will roll over from
FFH in RAM to 0100H in XRAM. The 11-bit stack pointer is
visible in the SP and SPH SFRs. The SP SFR is located at 81H
as with a standard 8052. The SPH SFR is located at B7H. The
3 LSBs of this SFR contain the three extra bits necessary to
extend the 8-bit stack pointer into an 11-bit stack pointer.
The SFR space is mapped into the upper 128 bytes of internal
data memory space and accessed by direct addressing only. It
provides an interface between the CPU and all on-chip peripherals. A block diagram showing the programming model of the
ADuC836 via the SFR area is shown in Figure 5.
8051
COMPATIBLE
CORE
07FFH
256 BYTES RAM
2K XRAM
UPPER 1792
BYTES OF
ON-CHIP XRAM
(DATA + STACK
FOR EXSP = 1,
DATA ONLY
FOR EXSP = 0)
CFG836.7 = 0
FFH
00H
CFG836.7 = 1
100H
256 BYTES OF
ON-CHIP DATA
RAM
(DATA +
STACK)
4 KBYTE
ELECTRICALLY
REPROGRAMMABLE
NONVOLATILE
FLASH/EE DATA
MEMORY
62 KBYTE ELECTRICALLY
REPROGRAMMABLE
NONVOLATILE FLASH/EE
PROGRAM MEMORY
128-BYTE
SPECIAL
FUNCTION
REGISTER
AREA
DUAL - ADCs
OTHER ON-CHIP
PERIPHERALS
TEMP SENSOR
CURRENT SOURCES
12-BIT DAC
SERIAL I/O
WDT, PSM
TIC, PLL
Figure 5. Programming Model
All registers, except the Program Counter (PC) and the four
general-purpose register banks, reside in the SFR area. The SFR
registers include control, configuration, and data registers that
provide an interface between the CPU and all on-chip peripherals.
Accumulator SFR (ACC)
LOWER 256
BYTES OF
ON-CHIP XRAM
(DATA ONLY)
00H
Figure 4. Extended Stack Pointer Operation
External Data Memory (External XRAM)
Just like a standard 8051 compatible core, the ADuC836 can
access external data memory using a MOVX instruction. The
MOVX instruction automatically outputs the various control
strobes required to access the data memory.
The ADuC836, however, can access up to 16 Mbytes of external
data memory. This is an enhancement of the 64 Kbytes external
data memory space available on a standard 8051 compatible core.
The external data memory is discussed in more detail in the
ADuC836 Hardware Design Considerations section.
ACC is the Accumulator Register, which is used for math
operations including addition, subtraction, integer multiplication,
and division, and Boolean bit manipulations. The mnemonics for
accumulator-specific instructions, refer to the Accumulator as A.
B SFR (B)
The B Register is used with the ACC for multiplication and
division operations. For other instructions, it can be treated as a
general-purpose scratch pad register.
Data Pointer (DPTR)
The Data Pointer is made up of three 8-bit registers, named DPP
(page byte), DPH (high byte), and DPL (low byte). These are
used to provide memory addresses for internal and external code
access and external data access. It may be manipulated as a 16-bit
register (DPTR = DPH, DPL), although INC DPTR instructions
will automatically carry over to DPP, or as three independent 8-bit
registers (DPP, DPH, DPL).
The ADuC836 supports dual data pointers. For more information,
refer to the Dual Data Pointer section.
–14–
REV. A
ADuC836
Stack Pointer (SP and SPH)
Table II. PCON SFR Bit Designations
The SP SFR is the stack pointer and is used to hold an internal
RAM address that is called the “top of the stack.” The SP Register
is incremented before data is stored, during PUSH and CALL
executions. While the Stack may reside anywhere in on-chip RAM,
the SP Register is initialized to 07H after a reset. This causes the
stack to begin at location 08H.
As mentioned earlier, the ADuC836 offers an extended 11-bit
stack pointer. The three extra bits that make up the 11-bit stack
pointer are the 3 LSBs of the SPH byte located at B7H.
Bit
Name
Description
7
6
5
4
3
2
1
0
SMOD
SERIPD
INT0PD
ALEOFF
GF1
GF0
PD
IDL
Double UART Baud Rate
SPI Power-Down Interrupt Enable
INT0 Power-Down Interrupt Enable
Disable ALE Output
General-Purpose Flag Bit
General-Purpose Flag Bit
Power-Down Mode Enable
Idle Mode Enable
Program Status Word (PSW)
The PSW SFR contains several bits reflecting the current status
of the CPU as detailed in Table I.
SFR Address
Power-On Default Value
Bit Addressable
D0H
00H
Yes
Table I. PSW SFR Bit Designations
Bit
Name
Description
7
6
5
4
3
CY
AC
F0
RS1
RS0
2
1
0
OV
F1
P
Carry Flag
Auxiliary Carry Flag
General-Purpose Flag
Register Bank Select Bits
RS1
RS0
Selected Bank
0
0
0
0
1
1
1
0
2
1
1
3
Overflow Flag
General-Purpose Flag
Parity Bit
Power Control SFR (PCON)
The PCON SFR contains bits for power saving options and
general-purpose status flags, as shown in Table II.
ADuC836 CONFIGURATION SFR (CFG836)
The CFG836 SFR contains the necessary bits to configure the
internal XRAM and the extended SP. By default it configures
the user into 8051 mode, i.e., extended SP is disabled, internal
XRAM is disabled.
SFR Address
Power-On Default Value
Bit Addressable
Table III. CFG836 SFR Bit Designations
Bit
Name
7
EXSP
6
5
4
3
2
1
0
The TIC (Wake-Up/RTC timer) can be used to accurately wake
up the ADuC836 from power-down at regular intervals. To use
the TIC to wake up the ADuC836 from power-down, the OSC_PD
bit in the PLLCON SFR must be clear and the TIC must be
enabled.
SFR Address
Power-On Default Value
Bit Addressable
REV. A
AFH
00H
No
87H
00H
No
–15–
Description
Extended SP Enable. If this bit is set, the
stack will roll over from SPH/SP = 00FFH to
0100H. If this bit is clear, the SPH SFR will
be disabled and the stack will roll over from
SP = FFH to SP = 00H.
–––
Reserved for Future Use
–––
Reserved for Future Use
–––
Reserved for Future Use
–––
Reserved for Future Use
–––
Reserved for Future Use
–––
Reserved for Future Use
XRAMEN XRAM Enable Bit. If this bit is set, the internal XRAM will be mapped into the lower
2 Kbytes of the external address space. If this
bit is clear, the internal XRAM will not be
accessible and the external data memory will
be mapped into the lower 2 Kbytes of external
data memory (see Figure 3).
ADuC836
COMPLETE SFR MAP
not implemented, i.e., no register exists at this location. If an
unoccupied location is read, an unspecified value is returned.
SFR locations that are reserved for future use are shaded
(RESERVED) and should not be accessed by user software.
Figure 6 shows a full SFR memory map and the SFR contents after RESET. NOT USED indicates unoccupied SFR
locations. Unoccupied locations in the SFR address space are
ISPI
WCOL
SPE
SPIM
CPOL
CPHA
SPR1
SPR0
FFH
0 FEH
0 FDH
0 FCH
0 FBH
0 FAH
1 F9H
0 F8H
0
F7H
0 F6H
0 F5H
0 F4H
0 F3H
0 F2H
0 F1H
0 F0H
0
SPICON
F8H
MDE
MCO
I2CM
MDI
I2CRS
I2CTX
RESERVED RESERVED
BITS
F0H
EFH
0 EEH
0 EDH
0 ECH
0 EBH
0 EAH
0 E9H
0 E8H
0
E7H
0
0 E5H
0 E4H
0 E3H
0 E2H
0 E1H
0 E0H
0
0 D8H
0
BITS
E8H
RDY0
DFH
CY
D7H
TF2
CFH
PRE3
C7H
RDY1
0 DEH
AC
0 D6H
EXF2
0 CEH
PRE2
0 C6H
PADC
BFH
RD
B7H
EA
AFH
0 BEH
WR
1 B6H
EADC
0 AEH
CAL
0 DDH
NOXREF
0 DCH
F0
0 D5H
RSI
GN0M
RESERVED
EAH
00H
0 CDH
TCLK
0 CCH
PRE1
0 C5H
PRE0
PS
T1
1 B5H
PT1
0 BBH
T0
INT1
1 B4H
ET2
0 ADH
WDIR
1 C3H
0 BCH
1 B3H
ES
ET1
0 ACH
OV
0 ABH
FI
0 D2H
EXEN2
0 CBH
0 C4H
PT2
0 BDH
0 D3H
0 D9H
TR2
CNT2
0 CAH
0 C9H
WDS
0 C2H
PX1
0 BAH
INT0
1 B2H
EX1
0 AAH
0 D0H
0
0 C8H
WDE
0 C1H
0
WDWR
0 C0H
PT0
0
PX0
B9H
0 B8H
TXD
1 B1H
0
ET0
1
EX0
0 A8H
0
SM0
1 A6H
SM1
1 A5H
1 A4H
SM2
1 A3H
REN
TB8
1 A2H
1 A1H
RB8
1 A0H
T1
9FH
0 9EH
0 9DH
0 9CH
0 9BH
0 9AH
0 99H
97H
1 96H
1 95H
1 94H
1 93H
1 92H
1 91H
D0H
00H
BITS
C8H
0 98H
TR1
TF0
TR0
IE1
IT1
T2
1 90H
IE0
0
1
IT0
8FH
0 8EH
0 8DH
0 8CH
0 8BH
0 8AH
0 89H
0 88H
0
87H
1 86H
1 85H
1 84H
1 83H
1 82H
1 81H
1 80H
1
EBH
1
53H
OF0H
00H
ADC0M
RESERVED
00H
RESERVED RESERVED RESERVED
E3H
80H
ADC0H
00H
DBH
00H
ADCMODE
ADC0CON
ADC1CON
D1H
D2H
D3H
07H
RCAP2L
RESERVED
CAH
IP
BITS
B8H
00H
GN1L
ECH
1
9AH
GN1H
EDH
OF1L
E4H
00H
ADC1L
00H
RESERVED RESERVED
59H
OF1H
E5H
80H
DCH
00H
SF
ICON
45H
D5H
RESERVED
TL2
CCH
TH2
00H
CDH
EDATA1
00H
PWM0H
B2H
PWM1L
00H
B3H
00H
BCH
00H
PWM1H
B4H
00H
RESERVED RESERVED
00H
A9H
RESERVED RESERVED
A0H
TIMECON
HTHSEC
2
SEC
2
MIN
2
00H
EDATA3
BEH
00H
RESERVED RESERVED
IEIP2
00H
HOUR
2
PWMCON
AEH
00H
INTVAL
BITS
A0H
FFH
A1H
00H
A2H
00H
A3H
00H
RESERVED RESERVED
BITS
98H
00H
P1
BITS
90H
88H
99H
NOT USED
00H
RESERVED RESERVED
00H
TMOD
89H
P0
BITS
00H
A5H
00H
T3FD
9DH
00H
A6H
00H
T3CON
9EH
00H
EADRH
C7H
00H
EDATA4
BFH
00H
SPH
B7H
00H
CFG836
AFH
00H
DPCON
A7H
00H
RESERVED
RESERVED RESERVED RESERVED RESERVED RESERVED
FFH
TCON
BITS
A4H
SBUF
03H
00H
EDATA2
BDH
DEH
PLLCON
D7H
00H
EADRL
RESERVED RESERVED
A8H
D4H
C6H
00H
B1H
PSMCON
DFH
00H
RESERVED RESERVED RESERVED
PWM0L
FFH
RESERVED RESERVED
ADC1H
DDH
2H
RESERVED RESERVED
B9H
00H
1
CHIPID
C2H
IE
BITS
CBH
ECON
00H
B0H
00H
RCAP2H
RESERVED
10H
C0H
BITS
00H
WDCON
BITS
SPIDAT
RESERVED
DAH
00H
SCON
R1
T2EX
TF1
1
FDH
BITS
P2
A7H
GN0H
OF0M
00H
P3
RXD
1 B0H
0 A9H
D8H
T2CON
CAP2
1
55H
E2H
00H
PSW
P
0 D1H
BITS
00H
RESERVED
E0H
ADCSTAT
ERR1
0 DAH
RS0
0 D4H
RCLK
ERR0
0 DBH
BITS
NOT USED
FCH
F7H
ACC
E6H
00H
00H
I2CCON
I2CI
DACCON
RESERVED RESERVED
FBH
04H
B
MDO
DACH
DACL
RESERVED RESERVED
BITS
00H
TL0
8AH
SP
TL1
00H
DPL
8BH
TH0
00H
DPH
8CH
00H
TH1
8DH
RESERVED RESERVED
00H
DPP
PCON
RESERVED RESERVED
80H
FFH
81H
07H
82H
00H
83H
00H
84H
00H
87H
00H
NOTES
1CALIBRATION COEFFICIENTS ARE PRECONFIGURED AT POWER-UP TO FACTORY CALIBRATED VALUES.
2THESE SFRs MAINTAIN THEIR PRERESET VALUES AFTER A RESET IF TIMECON.0 = 1.
SFR MAP KEY:
THESE BITS ARE CONTAINED IN THIS BYTE.
BIT MNEMONIC
BIT BIT ADDRESS
RESET DEFAULT
BIT VALUE
IE0
89H
TCON
IT0
0 88H
0
88H
00H
MNEMONIC
RESET DEFAULT VALUE
SFR ADDRESS
SFR NOTE:
SFRs WHOSE ADDRESSES END IN 0H OR 8H ARE BIT ADDRESSABLE.
Figure 6. Special Function Register Locations and Their Reset Default Values
–16–
REV. A
ADuC836
ADC SFR INTERFACE
Both ADCs are controlled and configured via a number of SFRs that are summarized here and described in more detail in the
following sections.
ADCSTAT
ADC Status Register. Holds general status of the
primary and auxiliary ADCs.
ADC0M/H
Primary ADC 16-bit conversion result is held in
these two 8-bit registers.
ADCMODE
ADC Mode Register. Controls general modes of
operation for primary and auxiliary ADCs
ADC1L/H
Auxiliary ADC 16-bit conversion result is held in
these two 8-bit registers.
ADC0CON
Primary ADC Control Register. Controls specific
configuration of primary ADC.
OF0M/H
Primary ADC 16-bit Offset Calibration Coefficient
is held in these two 8-bit registers.
ADC1CON
Auxiliary ADC Control Register. Controls
specific configuration of auxiliary ADC.
OF1L/H
Auxiliary ADC 16-bit Offset Calibration Coefficient
is held in these two 8-bit registers.
SF
Sinc Filter Register. Configures the decimation
factor for the Sinc3 filter and thus the primary
and auxiliary ADC update rates.
GN0M/H
Primary ADC 16-bit Gain Calibration Coefficient
is held in these two 8-bit registers.
ICON
Current Source Control Register. Allows the user
to control of the various on-chip current source
options.
GN1L/H
Auxiliary ADC 16-bit Gain Calibration Coefficient
is held in these two 8-bit registers.
ADCSTAT (ADC Status Register)
This SFR reflects the status of both ADCs including data ready, calibration, and various (ADC related) error and warning conditions
such as reference detect and conversion overflow/underflow flags.
SFR Address
D8H
Power-On Default Value
00H
Bit Addressable
Yes
Table IV. ADCSTAT SFR Bit Designations
Bit
Name
Description
7
RDY0
Ready Bit for Primary ADC.
Set by hardware on completion of ADC conversion or calibration cycle.
Cleared directly by the user or indirectly by writing to the mode bits to start another primary ADC conversion
or calibration. The primary ADC is inhibited from writing further results to its data or calibration registers
until the RDY0 bit is cleared.
6
RDY1
Ready Bit for Auxiliary ADC. Same definition as RDY0 referred to the auxiliary ADC.
5
CAL
Calibration Status Bit.
Set by hardware on completion of calibration.
Cleared indirectly by a write to the mode bits to start another ADC conversion or calibration.
4
NOXREF
No External Reference Bit (only active if primary or auxiliary ADC is active).
Set to indicate that one or both of the REFIN pins is floating or the applied voltage is below a specified threshold.
When set, conversion results are clamped to all ones, if using external reference.
Cleared to indicate valid VREF.
3
ERR0
Primary ADC Error Bit.
Set by hardware to indicate that the result written to the primary ADC data registers has been clamped to all
zeros or all ones. After a calibration, this bit also flags error conditions that caused the calibration registers not
to be written.
Cleared by a write to the mode bits to initiate a conversion or calibration.
2
ERR1
Auxiliary ADC Error Bit. Same definition as ERR0 referred to the auxiliary ADC.
1
–––
Reserved for Future Use
0
–––
Reserved for Future Use
REV. A
–17–
ADuC836
ADCMODE (ADC Mode Register)
Used to control the operational mode of both ADCs.
SFR Address
D1H
Power-On Default Value
00H
Bit Addressable
No
Table V. ADCMODE SFR Bit Designations
Bit
Name
Description
7
–––
Reserved for Future Use
6
–––
Reserved for Future Use
5
ADC0EN
Primary ADC Enable.
Set by the user to enable the primary ADC and place it in the mode selected in MD2–MD0, below.
Cleared by the user to place the primary ADC in power-down mode.
4
ADC1EN
Auxiliary ADC Enable.
Set by the user to enable the auxiliary ADC and place it in the mode selected in MD2–MD0, below.
Cleared by the user to place the auxiliary ADC in power-down mode.
3
–––
Reserved for Future Use
2
MD2
Primary and Auxiliary ADC Mode bits.
1
MD1
These bits select the operational mode of the enabled ADC as follows:
0
MD0
MD2
0
0
MD1
0
0
MD0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
ADC Power-Down Mode (Power-On Default)
Idle Mode. The ADC filter and modulator are held in a reset state although the
modulator clocks are still provided.
Single Conversion Mode. A single conversion is performed on the enabled ADC.
On completion of the conversion, the ADC data registers (ADC0H/M and/or ADC1H/L)
are updated, the relevant flags in the ADCSTAT SFR are written, and power-down is
re-entered with the MD2–MD0 accordingly being written to 000.
Continuous Conversion. The ADC data registers are regularly updated at the selected
update rate (see SF Register).
Internal Zero-Scale Calibration. Internal short automatically connected to the enabled
ADC input(s).
Internal Full-Scale Calibration. Internal or external VREF (as determined by XREF0
and XREF1 bits in ADC0/1CON) is automatically connected to the enabled ADC
input(s) for this calibration.
System Zero-Scale Calibration. User should connect system zero-scale input to the
enabled ADC input(s) as selected by CH1/CH0 and ACH1/ACH0 bits in the
ADC0/1CON Register.
System Full-Scale Calibration. User should connect system full-scale input to the
enabled ADC input(s) as selected by the CH1/CH0 and ACH1/ACH0 bits in the
ADC0/1CON Register.
NOTES
1. Any change to the MD bits will immediately reset both ADCs. A write to the MD2–0 bits with no change is also treated as a reset. (See exception to this in Note 3.)
2. If ADC0CON is written when ADC0EN = 1, or if ADC0EN is changed from 0 to 1, then both ADCs are also immediately reset. In other words, the primary ADC is
given priority over the auxiliary ADC, and any change requested on the primary ADC is immediately responded to.
3. On the other hand, if ADC1CON is written or if ADC1EN is changed from 0 to 1, only the auxiliary ADC is reset. For example, if the primary ADC is continuously converting
when the auxiliary ADC change or enable occurs, the primary ADC continues undisturbed. Rather than allow the auxiliary ADC to operate with a phase difference from
the primary ADC, the auxiliary ADC will fall into step with the outputs of the primary ADC. The result is that the first conversion time for the auxiliary ADC will be
delayed up to three outputs while the auxiliary ADC update rate is synchronized to the primary ADC.
4. Once ADCMODE has been written with a calibration mode, the RDY0/1 bits (ADCSTAT) are immediately reset and the calibration commences. On completion, the appropriate
calibration registers are written, the relevant bits in ADCSTAT are written, and the MD2–0 bits are reset to 000 to indicate the ADC is back in Power-Down mode.
5. Any calibration request of the auxiliary ADC while the temperature sensor is selected will fail to complete. Although the RDY1 bit will be set at the end of the calibration
cycle, no update of the calibration SFRs will take place and the ERR1 bit will be set.
6. Calibrations are performed at maximum SF (see SF SFR) value, guaranteeing optimum calibration operation.
–18–
REV. A
ADuC836
ADC0CON (Primary ADC Control Register) and ADC1CON (Auxiliary ADC Control Register)
The ADC0CON and ADC1CON SFRs are used to configure the primary and auxiliary ADC for reference and channel selection,
unipolar or bipolar coding and, in the case of the primary ADC, range (the auxiliary ADC operates on a fixed input range of ±VREF).
ADC0CON
Primary ADC Control SFR
ADC1CON
Auxiliary ADC Control SFR
SFR Address
D2H
SFR Address
D3H
Power-On Default Value 07H
Power-On Default Value
00H
Bit Addressable
No
Bit Addressable
No
Table VI. ADC0CON SFR Bit Designations
Bit
Name
Description
7
6
–––
XREF0
5
4
CH1
CH0
3
UNI0
2
1
0
RN2
RN1
RN0
Reserved for Future Use
Primary ADC External Reference Select Bit.
Set by user to enable the primary ADC to use the external reference via REFIN(+)/REFIN(–).
Cleared by user to enable the primary ADC to use the internal band gap reference (VREF = 1.25 V).
Primary ADC Channel Selection Bits.
Written by the user to select the differential input pairs used by the primary ADC as follows:
CH1
CH0
Positive Input
Negative Input
0
0
AIN1
AIN2
0
1
AIN3
AIN4
1
0
AIN2
AIN2 (Internal Short)
1
1
AIN3
AIN2
Primary ADC Unipolar Bit.
Set by user to enable unipolar coding, i.e., zero differential input will result in 000000H output.
Cleared by user to enable bipolar coding, i.e., zero differential input will result in 800000H output.
Primary ADC Range Bits.
Written by the user to select the primary ADC input range as follows:
RN2
RN1
RN0
Selected Primary ADC Input Range (VREF = 2.5 V)
0
0
0
±20 mV
(0 mV–20 mV in Unipolar Mode)
0
0
1
±40 mV
(0 mV–40 mV in Unipolar Mode)
0
1
0
±80 mV
(0 mV–80 mV in Unipolar Mode)
0
1
1
±160 mV
(0 mV–160 mV in Unipolar Mode)
1
0
0
±320 mV
(0 mV–320 mV in Unipolar Mode)
1
0
1
±640 mV
(0 mV–640 mV in Unipolar Mode)
1
1
0
±1.28 V
(0 V–1.28 V in Unipolar Mode)
1
1
1
±2.56 V
(0 V–2.56 V in Unipolar Mode)
Table VII. ADC1CON SFR Bit Designations
Bit
Name
Description
7
6
–––
XREF1
5
4
ACH1
ACH0
3
UNI1
2
1
0
–––
–––
–––
Reserved for Future Use
Auxiliary ADC External Reference Bit.
Set by user to enable the auxiliary ADC to use the external reference via REFIN(+)/REFIN(–).
Cleared by user to enable the auxiliary ADC to use the internal band gap reference.
Auxiliary ADC Channel Selection Bits.
Written by the user to select the single-ended input pins used to drive the auxiliary ADC as follows:
ACH1 ACH0 Positive Input
Negative Input
0
0
AIN3
AGND
0
1
AIN4
AGND
1
0
Temp Sensor
AGND (Temp Sensor routed to the ADC input)
1
1
AIN5
AGND
Auxiliary ADC Unipolar Bit.
Set by user to enable unipolar coding, i.e., zero input will result in 0000H output.
Cleared by user to enable bipolar coding, i.e., zero input will result in 8000H output.
Reserved for Future Use
Reserved for Future Use
Reserved for Future Use
NOTES
1. When the temperature sensor is selected, user code must select internal reference via XREF1 bit above and clear the UNI1 bit (ADC1CON.3) to select bipolar coding.
2. The temperature sensor is factory calibrated to yield conversion results 8000H at 0°C.
3. A +1°C change in temperature will result in a +1 LSB change in the ADC1H Register ADC conversion result.
REV. A
–19–
ADuC836
ADC0H/ADC0M (Primary ADC Conversion Result Registers)
These two 8-bit registers hold the 16-bit conversion result from the primary ADC.
SFR Address
Power-On Default Value
Bit Addressable
ADC0H
ADC0M
00H
No
High Data Byte
Middle Data Byte
ADC0H, ADC0M
ADC0H, ADC0M
DBH
DAH
ADC1H/ADC1L (Auxiliary ADC Conversion Result Registers)
These two 8-bit registers hold the 16-bit conversion result from the auxiliary ADC.
SFR Address
Power-On Default Value
Bit Addressable
ADC1H
ADC1L
00H
No
High Data Byte
Low Data Byte
ADC1H, ADC1L
ADC1H, ADC1L
DDH
DCH
OF0H/OF0M (Primary ADC Offset Calibration Registers*)
These two 8-bit registers hold the 16-bit offset calibration coefficient for the primary ADC. These registers are configured at power-on
with a factory default value of 800000H. However, these bytes will be automatically overwritten if an internal or system zero-scale
calibration of the primary ADC is initiated by the user via MD2–0 bits in the ADCMODE Register.
SFR Address
Power-On Default Value
Bit Addressable
OF0H
OF0M
80000H
No
Primary ADC Offset Coefficient High Byte
Primary ADC Offset Coefficient Middle Byte
OF0H, OF0M respectively
OF0H, OF0M
E3H
E2H
OF1H/OF1L (Auxiliary ADC Offset Calibration Registers*)
These two 8-bit registers hold the 16-bit offset calibration coefficient for the auxiliary ADC. These registers are configured at power-on
with a factory default value of 8000H. However, these bytes will be automatically overwritten if an internal or system zero-scale calibration
of the auxiliary ADC is initiated by the user via the MD2–0 bits in the ADCMODE Register.
SFR Address
Power-On Default Value
Bit Addressable
OF1H
OF1L
8000H
No
Auxiliary ADC Offset Coefficient High Byte
Auxiliary ADC Offset Coefficient Low Byte
OF1H and OF1L, respectively
OF1H, OF1L
E5H
E4H
GN0H/GN0M (Primary ADC Gain Calibration Registers*)
These two 8-bit registers hold the 16-bit gain calibration coefficient for the primary ADC. These registers are configured at power-on
with a factory-calculated internal full-scale calibration coefficient. Every device will have an individual coefficient. However, these bytes
will be automatically overwritten if an internal or system full-scale calibration of the primary ADC is initiated by the user via MD2–0
bits in the ADCMODE Register.
SFR Address
Power-On Default Value
Bit Addressable
GN0H
GN0M
No
Primary ADC Gain Coefficient High Byte
Primary ADC Gain Coefficient Middle Byte
Configured at Factory Final Test; See Notes above.
GN0H, GN0M
EBH
EAH
GN1H/GN1L (Auxiliary ADC Gain Calibration Registers*)
These two 8-bit registers hold the 16-bit gain calibration coefficient for the auxiliary ADC. These registers are configured at power-on
with a factory-calculated internal full-scale calibration coefficient. Every device will have an individual coefficient. However, these bytes
will be automatically overwritten if an internal or system full-scale calibration of the auxiliary ADC is initiated by the user via MD2–0
bits in the ADCMODE Register.
SFR Address
Power-On Default Value
Bit Addressable
GN1H
GN1L
No
Auxiliary ADC Gain Coefficient High Byte
Auxiliary ADC Gain Coefficient Low Byte
Configured at Factory Final Test; see notes above.
GN1H, GN1L
EDH
ECH
*These registers can be overwritten by user software only if Mode bits MD0–2 (ADCMODE SFR) are zero.
–20–
REV. A
ADuC836
SF (Sinc Filter Register)
The number in this register sets the decimation factor and thus
the output update rate for the primary and auxiliary ADCs. This
SFR cannot be written by user software while either ADC is active.
The update rate applies to both primary and auxiliary ADCs and
is calculated as follows:
f ADC =
where:
1
1
×
× f MOD
3 8 × SF
value for the SF Register is 45H, resulting in a default ADC update
rate of just under 20 Hz. Both ADC inputs are chopped to minimize offset errors, which means that the settling time for a single
conversion, or the time to a first conversion result in Continuous
Conversion mode, is 2  tADC. As mentioned earlier, all calibration cycles will be carried out automatically with a maximum, i.e.,
FFH, SF value to ensure optimum calibration performance. Once
a calibration cycle has completed, the value in the SF Register will
be that programmed by user software.
fADC = ADC Output Update Rate
fMOD = Modulator Clock Frequency = 32.768 kHz
SF = Decimal Value of SF Register
The allowable range for SF is 0DH to FFH. Examples of SF
values and corresponding conversion update rates (fADC) and conversion times (tADC) are shown in Table VIII. The power-on default
Table VIII. SF SFR Bit Designations
SF(dec)
SF(hex)
fADC(Hz)
tADC(ms)
13
69
255
0D
45
FF
105.3
19.79
5.35
9.52
50.34
186.77
ICON (Current Sources Control Register)
The icon SFR is used to control and configure the various excitation and burnout current source options available on-chip.
SFR Address
Power-On Default Value
Bit Addressable
D5H
00H
No
Table IX. ICON SFR Bit Designations
Bit
Name
Description
7
–––
Reserved for Future Use
6
BO
Burnout Current Enable Bit.
Set by user to enable both transducer burnout current sources in the primary ADC signal paths.
Cleared by the user to disable both transducer burnout current sources.
5
ADC1IC
Auxiliary ADC Current Correction Bit. Set by user to allow scaling of the auxiliary ADC by an internal current
source calibration word.
4
ADC0IC
Primary ADC Current Correction Bit.
Set by user to allow scaling of the primary ADC by an internal current source calibration word.
3
I2PIN*
Current Source-2 Pin Select Bit.
Set by user to enable current source-2 (200 A) to external Pin 3 (P1.2/DAC/IEXC1).
Cleared by user to enable current source-2 (200 A) to external Pin 4 (P1.3/AIN5/IEXC2).
2
I1PIN*
Current Source-1 Pin Select Bit.
Set by user to enable current source-1 (200 A) to external Pin 4 (P1.3/AIN5/IEXC2).
Cleared by user to enable current source-1 (200 A) to external Pin 3 (P1.2/DAC/IEXC1).
1
I2EN
Current Source-2 Enable Bit.
Set by user to turn on excitation current source-2 (200 A).
Cleared by user to turn off excitation current source-2 (200 A).
0
I1EN
Current Source-1 Enable Bit.
Set by user to turn on excitation current source-1 (200 A).
Cleared by user to turn off excitation current source-1 (200 A).
*Both current sources can be enabled to the same external pin, yielding a 400 A current source.
REV. A
–21–
ADuC836
PRIMARY AND AUXILIARY ADC NOISE PERFORMANCE
via the Sinc Filter (SF) SFR. It is important to note that the
peak-to-peak resolution figures represent the resolution for which
there will be no code flicker within a six-sigma limit.
Tables X, XI, and XII show the output rms noise in mV and output
peak-to-peak resolution in bits (rounded to the nearest 0.5 LSB)
for some typical output update rates on both the primary and
auxiliary ADCs. The numbers are typical and are generated at a
differential input voltage of 0 V. The output update rate is selected
The QuickStart Development system PC software comes complete with an ADC noise evaluation tool. This tool can be easily
used with the evaluation board to see these figures from silicon.
Table X. Primary ADC, Typical Output RMS Noise (V)
Typical Output RMS Noise vs. Input Range and Update Rate; Output RMS Noise in V
SF
Word
Data Update
Rate (Hz)
20 mV
40 mV
80 mV
Input Range
160 mV
320 mV
640 mV
1.28 V
2.56 V
13
69
255
105.3
19.79
5.35
1.50
0.60
0.35
1.50
0.65
0.35
1.60
0.65
0.37
1.75
0.65
0.37
3.50
0.65
0.37
4.50
0.95
0.51
6.70
1.40
0.82
11.75
2.30
1.25
Table XI. Primary ADC, Peak-to-Peak Resolution (Bits)
Peak-to-Peak Resolution vs. Input Range and Update Rate; Peak-to-Peak Resolution in Bits
SF
Word
Data Update
Rate (Hz)
20 mV
40 mV
80 mV
Input Range
160 mV
320 mV
640 mV
1.28 V
2.56 V
13
69
255
105.3
19.79
5.35
12
13.5
14
13
14
15
14
15
16
15
16
16
15
16
16
15.5
16
16
16
16
16
16
16
16
Typical RMS Resolution vs. Input Range and Update Rate: RMS Resolution in Bits*
SF
Word
Data Update
Rate (Hz)
20 mV
40 mV
80 mV
Input Range
160 mV
320 mV
640 mV
1.28 V
2.56 V
13
69
255
105.3
19.79
5.35
14.7
16
16
15.7
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
*Based on a six-sigma limit, the rms resolution is 2.7 bits greater than the peak-to-peak resolution.
Table XII. Auxiliary ADC
Peak-to-Peak Resolution vs. Update Rate1
Peak-to-Peak Resolution in Bits
Typical Output RMS Noise vs. Update Rate*
Output RMS Noise in V
SF
Data Update
Rate (Hz)
Input Range
Word
2.5 V
SF
Word
Data Update
Rate (Hz)
Input Range
2.5 V
13
69
255
105.3
19.79
5.35
10.75
2.00
1.15
13
69
255
105.3
19.79
5.35
162
16
16
*ADC converting in Bipolar mode
NOTES
1
ADC converting in Bipolar mode
2
In Unipolar mode, peak-to-peak resolution at 105 Hz is 15 bits.
–22–
REV. A
ADuC836
PRIMARY AND AUXILIARY ADC CIRCUIT DESCRIPTION
Overview
The ADuC836 incorporates two independent - ADCs (primary
and auxiliary) with on-chip digital filtering intended for the measurement of wide dynamic range, low frequency signals such as
those in weigh-scale, strain gage, pressure transducer, or temperature measurement applications.
Primary ADC
This ADC is intended to convert the primary sensor input. The
input is buffered and can be programmed for one of eight input
ranges from ±20 mV to ±2.56 V being driven from one of three
differential input channel options AIN1/2, AIN3/4, or AIN3/2.
The input channel is internally buffered, allowing the part to
handle significant source impedances on the analog input and
PROGRAMMABLE GAIN
AMPLIFIER
ANALOG INPUT CHOPPING
BURNOUT CURRENTS
TWO 100nA BURNOUT
CURRENTS ALLOW THE
USER TO EASILY DETECT
IF A TRANSDUCER HAS
BURNED OUT OR GONE
OPEN-CIRCUIT.
THE PROGRAMMABLE
GAIN AMPLIFIER ALLOWS
EIGHT UNIPOLAR AND
EIGHT BIPOLAR INPUT
RANGES FROM 20mV TO
2.56V (EXT V REF = 2.5V).
THE INPUTS ARE
ALTERNATELY REVERSED
THROUGH THE
CONVERSION CYCLE.
CHOPPING YIELDS
EXCELLENT ADC OFFSET
AND OFFSET DRIFT
PERFORMANCE.
allowing R/C filtering (for noise rejection or RFI reduction) to be
placed on the analog inputs if required. On-chip burnout currents
can also be turned on. These currents can be used to check that
a transducer on the selected channel is still operational before
attempting to take measurements.
The ADC employs a - conversion technique to realize up to
16 bits of no missing codes performance. The - modulator
converts the sampled input signal into a digital pulse train whose
duty cycle contains the digital information. A Sinc3 programmable
low-pass filter is then employed to decimate the modulator output
data stream to give a valid data conversion result at programmable
output rates from 5.35 Hz (186.77 ms) to 105.03 Hz (9.52 ms). A
chopping scheme is also employed to minimize ADC offset errors.
A block diagram of the primary ADC is shown in Figure 7.
DIFFERENTIAL
REFERENCE
THE EXTERNAL REFERENCE
INPUT TO THE ADuC836 IS
DIFFERENTIAL AND
FACILITATES RATIOMETRIC
OPERATION. THE EXTERNAL
REFERENCE VOLTAGE IS
SELECTED VIA THE XREF0 BIT
IN ADC0CON.
REFERENCE DETECT
CIRCUITRY TESTS FOR OPEN OR
SHORTED REFERENCE INPUTS.
- ADC
OUTPUT AVERAGE
THE - ARCHITECTURE
ENSURES 24 BITS NO
MISSING CODES. THE
ENTIRE - ADC IS
CHOPPED TO REMOVE
DRIFT ERROR.
AS PART OF THE CHOPPING
IMPLEMENTATION, EACH
DATA-WORD OUTPUT
FROM THE FILTER IS
SUMMED AND AVERAGED
WITH ITS PREDECESSOR
TO NULL ADC CHANNEL
OFFSET ERRORS.
REFIN(–) REFIN(+)
AVDD
- ADC
AIN1
AIN2
BUFFER
MUX
PGA
-
MODULATOR
PROGRAMMABLE
DIGITAL
FILTER
OUTPUT
AVERAGE
OUTPUT
SCALING
DIGTAL OUTPUT
RESULT WRITTEN
TO ADC0H/M/L
SFRS
AIN3
CHOP
AIN4
AGND
CHOP
OUTPUT SCALING
ANALOG MULTIPLEXER
A DIFFERENTIAL MULTIPLEXER
ALLOWS SELECTION OF THREE
FULLY DIFFERENTIAL PAIR OPTIONS AND
ADDITIONAL INTERNAL SHORT OPTION
(AIN2–AIN2). THE MULTIPLEXER IS
CONTROLLED VIA THE CHANNEL
SELECTION BITS IN ADC0CON.
BUFFER AMPLIFIER
THE BUFFER AMPLIFIER
PRESENTS A HIGH
IMPEDANCE INPUT STAGE
FOR THE ANALOG INPUTS,
ALLOWING SIGNIFICANT
EXTERNAL SOURCE
IMPEDANCES.
PROGRAMMABLE
DIGITAL FILTER
- MODULATOR
THE MODULATOR PROVIDES
A HIGH FREQUENCY 1-BIT
DATA STREAM (THE OUTPUT
OF WHICH IS ALSO CHOPPED)
TO THE DIGITAL FILTER,
THE DUTY CYCLE OF WHICH
REPRESENTS THE SAMPLED
ANALOG INPUT VOLTAGE.
THE SINC3 FILTER REMOVES
QUANTIZATION NOISE INTRODUCED
BY THE MODULATOR. THE UPDATE
RATE AND BANDWIDTH OF THIS
FILTER ARE PROGRAMMABLE
VIA THE SF SFR.
Figure 7. Primary ADC Block Diagram
REV. A
–23–
THE OUPUT WORD FROM THE
DIGITAL FILTER IS SCALED
BY THE CALIBRATION
COEFFICIENTS BEFORE
BEING PROVIDED AS
THE CONVERSION RESULT.
ADuC836
Auxiliary ADC
The auxiliary ADC is intended to convert supplementary inputs
such as those from a cold junction diode or thermistor. This ADC
is not buffered and has a fixed input range of 0 V to 2.5 V (assuming
an external 2.5 V reference). The single-ended inputs can be driven
from AIN3, AIN4, or AIN5 pins, or directly from the on-chip
temperature sensor voltage. A block diagram of the auxiliary ADC
is shown in Figure 8.
Analog Input Channels
The primary ADC has four associated analog input pins (labeled
AIN1 to AIN4) that can be configured as two fully differential input
channels. Channel selection bits in the ADC0CON SFR detailed
in Table VI allow three combinations of differential pair selection
as well as an additional shorted input option (AIN2–AIN2).
The auxiliary ADC has three external input pins (labeled AIN3
to AIN5) as well as an internal connection to the on-chip temperature sensor. All inputs to the auxiliary ADC are single-ended
inputs referenced to the AGND on the part. Channel selection
bits in the ADC1CON SFR detailed in Table VII allow selection
of one of four inputs.
Two input multiplexers switch the selected input channel to the
on-chip buffer amplifier in the case of the primary ADC and
directly to the - modulator input in the case of the auxiliary
ADC. When the analog input channel is switched, the settling
time of the part must elapse before a new valid word is available
from the ADC.
DIFFERENTIAL REFERENCE
ANALOG INPUT CHOPPING
THE INPUTS ARE ALTERNATELY
REVERSED THROUGH THE
CONVERSION CYCLE. CHOPPING
YIELDS EXCELLENT ADC
OFFSET AND OFFSET DRIFT
PERFORMANCE.
THE EXTERNAL REFERENCE INPUT
TO THE ADuC836 IS DIFFERENTIAL
AND FACILITATES RATIOMETRIC
OPERATION. THE EXTERNAL
REFERENCE VOLTAGE IS SELECTED
VIA THE XREF1 BIT IN ADC1CON.
REFERENCE DETECT
CIRCUITRY TESTS FOR OPEN OR
SHORTED REFERENCE INPUTS.
OUTPUT AVERAGE
- ADC
AS PART OF THE CHOPPING
IMPLEMENTATION, EACH
DATA-WORD OUTPUT
FROM THE FILTER IS
SUMMED AND AVERAGED
WITH ITS PREDECESSOR
TO NULL ADC CHANNEL
OFFSET ERRORS.
THE - ARCHITECTURE
ENSURES 16 BITS NO MISSING
CODES. THE ENTIRE - ADC
IS CHOPPED TO REMOVE
DRIFT ERRORS.
REFIN(–) REFIN(+)
- ADC
AIN3
AIN4
AIN5
ON-CHIP
TEMPERATURE
SENSOR
-
MODULATOR
MU
PROGRAMMABLE
DIGITAL FILTER
OUTPUT
AVERAGE
OUTPUT
SCALING
DIGTAL OUTPUT
RESULT WRITTEN
TO ADC1H/L SFRs
MUX
X
CHOP
CHOP
OUTPUT SCALING
ANALOG MULTIPLEXER
A DIFFERENTIAL MULTIPLEXER
ALLOWS SELECTION OF THREE
EXTERNAL SINGLE ENDED INPUTS
OR THE ON-CHIP TEMP. SENSOR.
THE MULTIPLEXER IS CONTROLLED
VIA THE CHANNEL SELECTION
BITS IN ADC1CON.
PROGRAMMABLE DIGITAL
FILTER
- MODULATOR
THE SINC3 FILTER REMOVES
QUANTIZATION NOISE INTRODUCED
BY THE MODULATOR. THE UPDATE
RATE AND BANDWIDTH OF THIS
FILTER ARE PROGRAMMABLE
VIA THE SF SFR.
THE MODULATOR PROVIDES A
HIGH FREQUENCY 1-BIT DATA
STREAM (THE OUTPUT OF WHICH
IS ALSO CHOPPED) TO THE
DIGITAL FILTER,
THE DUTY CYCLE OF WHICH
REPRESENTS THE SAMPLED
ANALOG INPUT VOLTAGE.
THE OUPUT WORD FROM THE
DIGITAL FILTER IS SCALED BY
THE CALIBRATION
COEFFICIENTS BEFORE
BEING PROVIDED AS
THE CONVERSION RESULT.
Figure 8. Auxiliary ADC Block Diagram
–24–
REV. A
ADuC836
Primary and Auxiliary ADC Inputs
19.372
The output of the Primary ADC multiplexer feeds into a high
impedance input stage of the buffer amplifier. As a result, the
primary ADC inputs can handle significant source impedances
and are tailored for direct connection to external resistive-type sensors like strain gages or Resistance Temperature Detectors (RTDs).
ADC INPUT VOLTAGE – mV
19.371
The auxiliary ADC, however, is unbuffered, resulting in higher
analog input current on the auxiliary ADC. It should be noted
that this unbuffered input path provides a dynamic load to the
driving source. Therefore, resistor/capacitor combinations on the
input pins can cause dc gain errors depending on the output
impedance of the source that is driving the ADC inputs.
19.367
19.366
800
2.56V
700
1.28V
600
640mV
500
320mV
400
160mV
300
80mV
200
40mV
100
20mV
ADC RANGE
Figure 9. Primary ADC Range Matching
The absolute input voltage range on the auxiliary ADC is restricted
to between AGND – 30 mV to AVDD + 30 mV. The slightly negative
absolute input voltage limit does allow the possibility of monitoring small signal bipolar signals using the single-ended auxiliary
ADC front end.
Programmable Gain Amplifier
The output from the buffer on the primary ADC is applied to the
input of the on-chip programmable gain amplifier (PGA). The
PGA can be programmed through eight different unipolar input
ranges and bipolar ranges. The PGA gain range is programmed
via the range bits in the ADC0CON SFR. With the external
reference select bit set in the ADC0CON SFR and an external
2.5 V reference, the unipolar ranges are 0 mV to 20 mV, 0 mV to
40 mV, 0 mV to 80 mV, 0 mV to 160 mV, 0 mV to 320 mV, 0 mV
to 640 mV, 0 V to 1.28 V, and 0 to 2.56 V; the bipolar ranges
are ±20 mV, ±40 mV, ±80 mV, ±160 mV, ±320 mV, ±640 mV,
±1.28 V, and ±2.56 V. These are the nominal ranges that should
appear at the input to the on-chip PGA. An ADC range matching
specification of 2 µV (typ) across all ranges means that calibration
need only be carried out at a single gain range and does not have
to be repeated when the PGA gain range is changed.
REV. A
19.368
19.364
SAMPLE COUNT 0
The absolute input voltage range on the primary ADC is restricted
to between AGND + 100 mV to AVDD – 100 mV. Care must be
taken in setting up the common-mode voltage and input voltage
range so that these limits are not exceeded; otherwise there will
be a degradation in linearity performance.
The auxiliary ADC does not incorporate a PGA and is configured
for a fixed single input range of 0 to VREF.
19.369
19.365
Analog Input Ranges
Typical matching across ranges is shown in Figure 9. Here, the
primary ADC is configured in bipolar mode with an external 2.5 V
reference, while just greater than 19 mV is forced on its inputs.
The ADC continuously converts the dc input voltage at an update
rate of 5.35 Hz, i.e., SF = FFH. In total, 800 conversion results are
gathered. The first 100 results are gathered with the primary ADC
operating in the ±20 mV range. The ADC range is then switched
to ±40 mV, 100 more conversion results are gathered, and so on,
until the last group of 100 samples is gathered with the ADC configured in the ±2.56 V range. From Figure 9, the variation in the
sample mean through each range, i.e., the range matching, is seen
to be of the order of 2 V.
19.370
Bipolar/Unipolar Inputs
The analog inputs on the ADuC836 can accept either unipolar
or bipolar input voltage ranges. Bipolar input ranges do not imply
that the part can handle negative voltages with respect to system
AGND.
Unipolar and bipolar signals on the AIN(+) input on the primary
ADC are referenced to the voltage on the respective AIN(–)
input. For example, if AIN(–) is 2.5 V and the primary ADC is
configured for an analog input range of 0 mV to 20 mV, the input
voltage range on the AIN(+) input is 2.5 V to 2.52 V. If AIN(–) is
2.5 V and the ADuC836 is configured for an analog input range
of 1.28 V, the analog input range on the AIN(+) input is 1.22 V to
3.78 V (i.e., 2.5 V ± 1.28 V).
As mentioned earlier, the auxiliary ADC input is a single-ended
input with respect to the system AGND. In this context, a bipolar
signal on the auxiliary ADC can only span 30 mV negative with
respect to AGND before violating the voltage input limits for
this ADC.
Bipolar or unipolar options are chosen by programming the primary and auxiliary Unipolar enable bits in the ADC0CON and
ADC1CON SFRs, respectively. This programs the relevant ADC
for either unipolar or bipolar operation. Programming for either
unipolar or bipolar operation does not change any of the input
signal conditioning; it simply changes the data output coding
and the points on the transfer function where calibrations occur.
When an ADC is configured for unipolar operation, the output
coding is natural (straight) binary with a zero differential input
voltage resulting in a code of 000 . . . 000, a midscale voltage
resulting in a code of 100 . . . 000, and a full-scale input voltage
resulting in a code of 111 . . . 111. When an ADC is configured
for bipolar operation, the coding is offset binary with a negative
full-scale voltage resulting in a code of 000 . . . 000, a zero differential voltage resulting in a code of 100 . . . 000, and a positive
full-scale voltage resulting in a code of 111 . . . 111.
–25–
ADuC836
Reference Input
Excitation Currents
The ADuC836’s reference inputs, REFIN(+) and REFIN(–),
provide a differential reference input capability. The commonmode range for these differential inputs is from AGND to AVDD.
The nominal reference voltage, VREF (REFIN(+) – REFIN(–)),
for specified operation is 2.5 V with the primary and auxiliary
reference enable bits set in the respective ADC0CON and/or
ADC1CON SFRs.
The ADuC836 also contains two identical, 200 µA constant current
sources. Both source current from AVDD to Pin 3 (IEXC1) or Pin 4
(IEXC2). These current sources are controlled via bits in the ICON
SFR shown in Table IX. They can be configured to source 200 µA
individually to both pins or a combination of both currents, i.e.,
400 µA, to either of the selected pins. These current sources can be
used to excite external resistive bridge or RTD sensors.
The part is also functional (although not specified for performance) when the XREF0 or XREF1 bits are 0, which enables the
on-chip internal band gap reference. In this mode, the ADCs will see
the internal reference of 1.25 V, therefore halving all input ranges.
As a result of using the internal reference voltage, a noticeable
degradation in peak-to-peak resolution will result. Therefore, for
best performance, operation with an external reference is strongly
recommended.
Reference Detect
In applications where the excitation (voltage or current) for the
transducer on the analog input also drives the reference voltage
for the part, the effect of the low frequency noise in the excitation
source will be removed as the application is ratiometric. If the
ADuC836 is not used in a ratiometric application, a low noise
reference should be used. Recommended reference voltage sources
for the ADuC836 include the AD780, REF43, and REF192.
It should also be noted that the reference inputs provide a high
impedance, dynamic load. Because the input impedance of each
reference input is dynamic, resistor/capacitor combinations on these
inputs can cause dc gain errors depending on the output impedance of the source that is driving the reference inputs. Reference
voltage sources, like those recommended above (e.g., AD780),
will typically have low output impedances and therefore decoupling
capacitors on the REFIN(+) input would be recommended.
Deriving the reference input voltage across an external resistor,
as shown in Figure 66, will mean that the reference input sees a
significant external source impedance. External decoupling on
the REFIN(+) and REFIN(–) pins would not be recommended
in this type of circuit configuration.
The ADuC836 includes on-chip circuitry to detect if the part has
a valid reference for conversions or calibrations. If the voltage
between the external REFIN(+) and REFIN(–) pins goes below
0.3 V or either the REFIN(+) or REFIN(–) inputs is open circuit,
the ADuC836 detects that it no longer has a valid reference. In this
case, the NOXREF bit of the ADCSTAT SFR is set to a 1. If the
ADuC836 is performing normal conversions and the NOXREF
bit becomes active, the conversion results revert to all 1s. It is not
necessary to continuously monitor the status of the NOXREF bit
when performing conversions. It is only necessary to verify its status
if the conversion result read from the ADC Data Register is all 1s.
If the ADuC836 is performing either an offset or gain calibration
and the NOXREF bit becomes active, the updating of the respective calibration registers is inhibited to avoid loading incorrect
coefficients to these registers, and the appropriate ERR0 or ERR1
bits in the ADCSTAT SFR are set. If the user is concerned about
verifying that a valid reference is in place every time a calibration is
performed, the status of the ERR0 or ERR1 bit should be checked
at the end of the calibration cycle.
- Modulator
A - ADC generally consists of two main blocks, an analog modulator and a digital filter. In the case of the ADuC836 ADCs, the
analog modulators consist of a difference amplifier, an integrator
block, a comparator, and a feedback DAC, as illustrated in Figure 10.
ANALOG
INPUT
COMPARATOR
INTEGRATOR
Burnout Currents
The primary ADC on the ADuC836 contains two 100 nA constant current generators: one sourcing current from AVDD to
AIN(+) and one sinking from AIN(–) to AGND. The currents
are switched to the selected analog input pair. Both currents are
either on or off, depending on the Burnout Current Enable
(BO) bit in the ICON SFR (see Table IX). These currents can
be used to verify that an external transducer is still operational
before attempting to take measurements on that channel. Once
the burnout currents are turned on, they will flow in the external
transducer circuit, and a measurement of the input voltage on
the analog input channel can be taken. If the resultant voltage
measured is full-scale, it indicates that the transducer has gone
open-circuit. If the voltage measured is 0 V, it indicates that the
transducer has short circuited. For normal operation, these burnout currents are turned off by writing a 0 to the BO bit in the
ICON SFR. The current sources work over the normal absolute
input voltage range specifications.
DIFFERENCE
AMP
HIGH
FREQUENCY
BIT STREAM
TO DIGITAL
FILTER
DAC
Figure 10. - Modulator Simplified Block Diagram
In operation, the analog signal sample is fed to the difference
amplifier along with the output of the feedback DAC. The difference between these two signals is integrated and fed to the
comparator. The output of the comparator provides the input to
the feedback DAC so the system functions as a negative feedback
loop that tries to minimize the difference signal. The digital data
that represents the analog input voltage is contained in the duty
cycle of the pulse train appearing at the output of the comparator.
This duty cycle data can be recovered as a data-word using a subsequent digital filter stage. The sampling frequency of the modulator
loop is many times higher than the bandwidth of the input signal.
The integrator in the modulator shapes the quantization noise
(which results from the analog-to-digital conversion) so that the
noise is pushed toward one-half of the modulator frequency.
–26–
REV. A
ADuC836
Digital Filter
0
The output of the - modulator feeds directly into the digital
filter. The digital filter then band-limits the response to a frequency
significantly lower than one-half of the modulator frequency. In
this manner, the 1-bit output of the comparator is translated into
a band-limited, low noise output from the ADuC836 ADCs.
–10
–20
–30
GAIN – dB
–40
The ADuC836 filter is a low-pass, SIN3 or (SINx/x)3 filter whose
primary function is to remove the quantization noise introduced
at the modulator. The cutoff frequency and decimated output
data rate of the filter are programmable via the SF (Sinc Filter)
SFR, as described in Table VIII.
–70
–90
–100
–110
–120
0
10
20
30
70
80
90
110
Figures 13 and 14 show the NMR for 50 Hz and 60 Hz across
the full range of SF word, i.e., SF = 13 dec to SF = 255 dec.
0
–10
–20
–30
GAIN – dB
–40
0
–10
–20
–50
–60
–70
–80
–30
–90
–40
–100
–50
–110
–60
–120
10
–70
30
50
70
90
–80
–90
110 130 150 170 190 210 230 250
SF – Decimal
Figure 13. 50 Hz Normal Mode Rejection vs. SF
–100
0
–110
–120
40
50
60
FREQUENCY – Hz
Figure 12. Filter Response, SF = 255 dec
It should also be noted that rejection of mains related frequency
components, i.e., 50 Hz and 60 Hz, is seen to be at a level of
>65 dB at 50 Hz and >100 dB at 60 Hz. This confirms the data
sheet specifications for 50 Hz/60 Hz Normal Mode Rejection
(NMR) at a 20 Hz update rate.
GAIN – dB
–60
–80
Figure 11 shows the frequency response of the ADC channel at
the default SF word of 69 dec or 45H, yielding an overall output
update rate of just under 20 Hz.
It should be noted that this frequency response allows frequency
components higher than the ADC Nyquist frequency to pass
through the ADC, in some cases without significant attenuation.
These components may, therefore, be aliased and appear in-band
after the sampling process.
–50
–10
0
10
20
30
40
50
60
70
FREQUENCY – Hz
80
90
100
110
–20
–30
Figure 11. Filter Response, SF = 69 dec
GAIN – dB
–40
The response of the filter, however, will change with SF word, as
can be seen in Figure 12, which shows >90 dB NMR at 50 Hz
and >70 dB NMR at 60 Hz when SF = 255 dec.
–50
–60
–70
–80
–90
–100
–110
–120
10
30
50
70
90
110 130 150 170 190 210 230 250
SF – Decimal
Figure 14. 60 Hz Normal Mode Rejection vs. SF
REV. A
–27–
ADuC836
ADC Chopping
Both ADCs on the ADuC836 implement a chopping scheme
whereby the ADC repeatedly reverses its inputs. The decimated
digital output words from the Sinc3 filters therefore have a positive
offset and negative offset term included.
As a result, a final summing stage is included in each ADC so that
each output word from the filter is summed and averaged with
the previous filter output to produce a new valid output result
to be written to the ADC data SFRs. In this way, while the ADC
throughput or update rate is as discussed earlier and illustrated in
Table VIII, the full settling time through the ADC (or the time to
a first conversion result) will actually be given by 2  tADC.
The chopping scheme incorporated in the ADuC836 ADC results
in excellent dc offset and offset drift specifications and is extremely
beneficial in applications where drift, noise rejection, and optimum
EMI rejection are important factors.
Calibration
The ADuC836 provides four calibration modes that can be programmed via the mode bits in the ADCMODE SFR detailed in
Table V. In fact, every ADuC836 has already been factory calibrated. The resultant Offset and Gain calibration coefficients
for both the primary and auxiliary ADCs are stored on-chip in
manufacturing-specific Flash/EE memory locations. At power-on
or after reset, these factory calibration coefficients are automatically downloaded to the calibration registers in the ADuC836
SFR space. Each ADC (primary and auxiliary) has dedicated
calibration SFRs, which have been described earlier as part of the
general ADC SFR description. However, the factory calibration
values in the ADC calibration SFRs will be overwritten if any
one of the four calibration options are initiated and that ADC is
enabled via the ADC enable bits in ADCMODE.
Even though an internal offset calibration mode is described
below, it should be recognized that both ADCs are chopped. This
chopping scheme inherently minimizes offset and means that an
internal offset calibration should never be required. Also, because
factory 5 V/25°C gain calibration coefficients are automatically
present at power-on an internal full-scale calibration will only be
required if the part is being operated at 3 V or at temperatures
significantly different from 25°C.
The ADuC836 offers internal or system calibration facilities. For
full calibration to occur on the selected ADC, the calibration
logic must record the modulator output for two different input
conditions: zero-scale and full-scale points. These points are
derived by performing a conversion on the different input voltages provided to the input of the modulator during calibration.
The result of the zero-scale calibration conversion is stored in the
Offset Calibration Registers for the appropriate ADC. The result
of the full-scale calibration conversion is stored in the Gain Calibration Registers for the appropriate ADC. With these readings,
the calibration logic can calculate the offset and the gain slope for
the input-to-output transfer function of the converter.
During an internal zero-scale or full-scale calibration, the respective
zero-scale input and full-scale inputs are automatically connected to
the ADC input pins internally to the device. A system calibration,
however, expects the system zero-scale and system full-scale voltages to be applied to the external ADC pins before the calibration
mode is initiated. In this way, external ADC errors are taken into
account and minimized as a result of system calibration. It should
also be noted that to optimize calibration accuracy, all ADuC836
ADC calibrations are carried out automatically at the slowest
update rate.
Internally in the ADuC836, the coefficients are normalized before
being used to scale the words coming out of the digital filter. The
offset calibration coefficient is subtracted from the result prior to
the multiplication by the gain coefficient.
From an operational point of view, a calibration should be treated
like another ADC conversion. A zero-scale calibration (if required)
should always be carried out before a full-scale calibration. System
software should monitor the relevant ADC RDY0/1 bit in the
ADCSTAT SFR to determine end of calibration via a polling
sequence or interrupt driven routine.
–28–
REV. A
ADuC836
ADuC836 Flash/EE Memory Reliability
NONVOLATILE FLASH/EE MEMORY
Flash/EE Memory Overview
The Flash/EE program and data memory arrays on the ADuC836
are fully qualified for two key Flash/EE memory characteristics:
Flash/EE Memory Cycling Endurance and Flash/EE Memory
Data Retention.
The ADuC836 incorporates Flash/EE memory technology
on-chip to provide the user with nonvolatile, in-circuit, reprogrammable code and data memory space. Flash/EE memory is
a relatively recent type of nonvolatile memory technology and is
based on a single transistor cell architecture. This technology is
basically an outgrowth of EPROM technology and was developed through the late 1980s. Flash/EE memory takes the flexible
in-circuit reprogrammable features of EEPROM and combines
them with the space efficient/density features of EPROM (see
Figure 15).
Endurance quantifies the ability of the Flash/EE memory to be
cycled through many program, read, and erase cycles. In real
terms, a single endurance cycle is composed of four independent,
sequential events, which are defined as:
a. Initial page erase sequence
b. Read/verify sequence
Because Flash/EE technology is based on a single transistor cell
architecture, a Flash memory array, like EPROM, can be implemented to achieve the space efficiencies or memory densities
required by a given design.
c. Byte program sequence
d. Second read/verify sequence
In reliability qualification, every byte in both the program and
data Flash/EE memory is cycled from 00H to FFH until a first
fail is recorded, signifying the endurance limit of the on-chip
Flash/EE memory.
Like EEPROM, flash memory can be programmed in-system
at a byte level, although it must first be erased; the erase being
performed in page blocks. Thus, flash memory is often and more
correctly referred to as Flash/EE memory.
As indicated in the Specification tables, the ADuC836 Flash/EE
Memory Endurance qualification has been carried out in
accordance with JEDEC Specification A117 over the industrial
temperature range of –40°C, +25°C, +85°C, and +125°C. The
results allow the specification of a minimum endurance figure
over supply and temperature of 100,000 cycles, with an endurance figure of 700,000 cycles being typical of operation at 25°C.
EEPROM
TECHNOLOGY
SPACE EFFICIENT/
DENSITY
IN-CIRCUIT
REPROGRAMMABLE
FLASH/EE MEMORY
TECHNOLOGY
Retention quantifies the ability of the Flash/EE memory to retain
its programmed data over time. Again, the ADuC836 has been
qualified in accordance with the formal JEDEC Retention Lifetime Specification (A117) at a specific junction temperature
(TJ = 55°C). As part of this qualification procedure, the Flash/EE
memory is cycled to its specified endurance limit described above,
before data retention is characterized. This means that the Flash/EE
memory is guaranteed to retain its data for its full specified retention lifetime every time the Flash/EE memory is reprogrammed.
It should also be noted that retention lifetime, based on an activation energy of 0.6 eV, will derate with TJ, as shown in Figure 16.
Figure 15. Flash/EE Memory Development
Overall, Flash/EE memory represents a step closer to the ideal
memory device that includes nonvolatility, in-circuit programmability, high density, and low cost. Incorporated into the ADuC836,
Flash/EE memory technology allows the user to update program
code space in-circuit, without the need to replace one-time programmable (OTP) devices at remote operating nodes.
Flash/EE Memory and the ADuC836
The ADuC836 provides two arrays of Flash/EE memory for user
applications. 62 Kbytes of Flash/EE program space are provided
on-chip to facilitate code execution without any external discrete ROM device requirements. The program memory can be
programmed in-circuit, using the serial download mode provided,
using conventional third party memory programmers, or via any
user defined protocol in User Download (ULOAD) mode.
A 4 Kbyte Flash/EE data memory space is also provided on-chip.
This may be used as a general-purpose, nonvolatile scratch pad
area. User access to this area is via a group of seven SFRs. This
space can be programmed at a byte level, although it must first be
erased in 4-byte pages.
300
250
RETENTION – Years
EPROM
TECHNOLOGY
A Single Flash/EE
Memory Endurance
Cycle
200
ADI SPECIFICATION
100 YEARS MIN.
AT TJ = 55C
150
100
50
0
40
50
60
70
80
90
TJ JUNCTION TEMPERATURE – C
100
110
Figure 16. Flash/EE Memory Data Retention
REV. A
–29–
ADuC836
Flash/EE Program Memory
(2) Parallel Programming
The ADuC836 contains a 64 Kbyte array of Flash/EE program
memory. The lower 62 Kbytes of this program memory are available to the user, and can be used for program storage or indeed
as additional NV data memory.
The Parallel Programming mode is fully compatible with conventional third party Flash or EEPROM device programmers.
A block diagram of the external pin configuration required to
support parallel programming is shown in Figure 18. In this mode,
Ports 0 and 2 operate as the external address bus interface, P3
operates as the external data bus interface, and P1.0 operates as
the Write Enable strobe. Port 1.1, P1.2, P1.3, and P1.4 are used
as a general configuration port that configures the device for various program and erase operations during parallel programming.
The upper 2 Kbytes of this Flash/EE program memory array contain permanently embedded firmware, allowing in-circuit serial
download, serial debug, and nonintrusive single pin emulation.
These 2 Kbytes of embedded firmware also contain a power-on
configuration routine that downloads factory calibrated coefficients to the various calibrated peripherals (ADC, temperature
sensor, current sources, band gap references, and so on).
This 2 Kbyte embedded firmware is hidden from user code.
Attempts to read this space will read 0s, i.e., the embedded firmware appears as NOP instructions to user code.
In normal operating mode (power-up default), the 62 Kbytes of
user Flash/EE program memory appear as a single block. This
block is used to store the user code, as shown in Figure 17.
EMBEDDED DOWNLOAD/DEBUG KERNEL
PERMANENTLY EMBEDDED FIRMWARE ALLOWS CODE
TO BE DOWNLOADED TO ANY OF THE 62 KBYTES OF
ON-CHIP PROGRAM MEMORY. THE KERNEL PROGRAM
APPEARS AS ‘NOP’ INSTRUCTIONS TO USER CODE.
FFFFH
2 KBYTE
F800H
USER PROGRAM MEMORY
62 KBYTES OF FLASH/EE PROGRAM MEMORY IS
AVAILABLE TO THE USER. ALL OF THIS SPACE CAN
BE PROGRAMMED FROM THE PERMANENTLY
EMBEDDED DOWNLOAD/DEBUG KERNEL OR IN
PARALLEL PROGRAMMING MODE.
62 KBYTE
F7FFH
Table XIII. Flash/EE Memory Parallel Programming Modes
P1.4
Port 1 Pins
P1.3 P1.2
P1.1
Programming Mode
0
0
0
0
1
0
0
1
0
1
0
0
1
1
0
1
0
0
1
1
1
0
1
1
0
All other codes
1
0
0
1
1
0
1
Erase Flash/EE Program,
Data, and Security Modes
Read Device Signature/ID
Program Code Byte
Program Data Byte
Read Code Byte
Read Data Byte
Program Security Modes
Read/Verify Security Modes
Redundant
5V
VDD
ADuC836
P3
GND
PROGRAM MODE
(SEE TABLE XIII)
0000H
COMMAND
ENABLE
Figure 17. Flash/EE Program Memory Map in Normal Mode
In Normal mode, the 62 Kbytes of Flash/EE program memory
can be programmed by serial downloading or parallel processing:
ENTRY
SEQUENCE
P1.1 -> P1.4
P1.0
GND
EA
GND
PSEN
VDD
P0
P2
P1.5 -> P1.7
PROGRAM
DATA
(D0–D7)
PROGRAM
ADDRESS
(A0–A13)
(P2.0 = A0)
(P1.7 = A13)
TIMING
RESET
(1) Serial Downloading (In-Circuit Programming)
The ADuC836 facilitates code download via the standard UART
serial port. The ADuC836 will enter Serial Download mode after
a reset or power cycle if the PSEN pin is pulled low through an
external 1 k resistor. Once in serial download mode, the hidden
embedded download kernel will execute. This allows the user to
download code to the full 62 Kbytes of Flash/EE program memory while the device is in circuit in its target application hardware.
Figure 18. Flash/EE Memory Parallel Programming
A PC serial download executable is provided as part of the
ADuC836 QuickStart development system. Application Note
uC004 fully describes the serial download protocol that is used
by the embedded download kernel. This Application Note is
available at www.analog.com/microconverter.
–30–
REV. A
ADuC836
Flash/EE Program Memory Security
User Download Mode (ULOAD)
In Figure 17 we can see that it was possible to use the 62 Kbytes
of Flash/EE program memory available to the user as one single
block of memory. In this mode, all of the Flash/EE memory is
read only to user code.
However, the Flash/EE program memory can also be written to
during runtime simply by entering ULOAD mode. In ULOAD
mode, the lower 56 Kbytes of program memory can be erased
and reprogrammed by user software, as shown in Figure 19.
ULOAD mode can be used to upgrade your code in the field via
any user defined download protocol. Configuring the SPI port on
the ADuC836 as a slave, it is possible to completely reprogram
the 56 Kbytes of Flash/EE program memory in only 5 seconds
(see Application Note uC007).
Alternatively, ULOAD mode can be used to save data to the
56 Kbytes of Flash/EE memory. This can be extremely useful in
data logging applications where the ADuC836 can provide up to
60 Kbytes of NV data memory on-chip (4 Kbytes of dedicated
Flash/EE data memory also exist).
The upper 6 Kbytes of the 62 Kbytes of Flash/EE program memory
are only programmable via serial download or parallel programming. This means that this space appears as read-only to user
code. Therefore, it cannot be accidently erased or reprogrammed
by erroneous code execution. This makes it very suitable to use
the 6 Kbytes as a bootloader. A Bootload Enable option exists in
the serial downloader to “Always RUN from E000h after Reset.”
If using a bootloader, this option is recommended to ensure that
the bootloader always executes correct code after reset.
Programming the Flash/EE program memory via ULOAD mode
is described in more detail in the description of ECON and also
in Application Note uC007.
EMBEDDED DOWNLOAD/DEBUG KERNEL
PERMANENTLY EMBEDDED FIRMWARE ALLOWS CODE
TO BE DOWNLOADED TO ANY OF THE 62 KBYTES OF
ON-CHIP PROGRAM MEMORY. THE KERNEL PROGRAM
APPEARS AS ‘NOP’ INSTRUCTIONS TO USER CODE.
62 KBYTES
OF USER
CODE
MEMORY
USER BOOTLOADER SPACE
THE USER BOOTLOADER SPACE
CAN BE PROGRAMMED IN
DOWNLOAD/DEBUG MODE VIA THE
KERNEL BUT IS READ ONLY WHEN
EXECUTING USER CODE
USER DOWNLOAD SPACE
EITHER THE DOWNLOAD/DEBUG KERNEL
OR USER CODE (IN ULOAD MODE) CAN
PROGRAM THIS SPACE.
The ADuC836 facilitates three modes of Flash/EE program memory
security. These modes can be independently activated, restricting access to the internal code space. These security modes can
be enabled as part of serial download protocol, as described
in Application Note uC004, or via parallel programming. The
ADuC836 offers the following security modes:
Lock Mode
This mode locks the code memory, disabling parallel programming of the program memory. However, reading the memory in
Parallel mode and reading the memory via a MOVC command
from external memory is still allowed. This mode is deactivated
by initiating an “erase code and data” command in Serial Download or Parallel Programming modes.
Secure Mode
This mode locks the code memory, disabling parallel programming of the program memory. Reading/verifying the memory
in Parallel mode and reading the internal memory via a MOVC
command from external memory is also disabled. This mode is
deactivated by initiating an “erase code and data” command in
Serial Download or Parallel Programming modes.
Serial Safe Mode
This mode disables serial download capability on the device.
If Serial Safe mode is activated and an attempt is made to reset
the part into Serial Download mode, i.e., RESET asserted and
deasserted with PSEN low, the part will interpret the serial download reset as a normal reset only. It will therefore not enter Serial
Download mode, but only execute a normal reset sequence.
Serial Safe mode can only be disabled by initiating an “erase code
and data” command in parallel programming mode.
FFFFH
2 KBYTE
F800H
F7FFH
6 KBYTE
E000H
DFFFH
56 KBYTE
0000H
Figure 19. Flash/EE Program Memory Map in
ULOAD Mode
REV. A
–31–
ADuC836
BYTE 2
(0FFDH)
BYTE 3
(0FFEH)
BYTE 4
(0FFFH)
3FEH
BYTE 1
(0FF8H)
BYTE 2
(0FF9H)
BYTE 3
(0FFAH)
BYTE 4
(0FFBH)
03H
BYTE 1
(000CH)
BYTE 2
(000DH)
BYTE 3
(000EH)
BYTE 4
(000FH)
02H
BYTE 1
(0008H)
BYTE 2
(0009H)
BYTE 3
(000AH)
BYTE 4
(000BH)
01H
BYTE 1
(0004H)
BYTE 2
(0005H)
BYTE 3
(0006H)
BYTE 4
(0007H)
BYTE 1
(0000H)
BYTE 2
(0001H)
BYTE 3
(0002H)
BYTE 4
(0003H)
00H
A block diagram of the SFR interface to the Flash/EE data
memory array is shown in Figure 20.
ECON—Flash/EE Memory Control SFR
BYTE
ADDRESSES
ARE GIVEN IN
BRACKETS
Programming of either the Flash/EE data memory or the Flash/EE
program memory is done through the Flash/EE Memory Control
SFR (ECON). This SFR allows the user to read, write, erase, or
verify the 4 Kbytes of Flash/EE data memory or the 56 Kbytes of
Flash/EE program memory.
EDATA4 SFR
BYTE 1
(0FFCH)
EDATA3 SFR
3FFH
EDATA2 SFR
PAGE ADDRESS
(EADRH/L)
The 4 Kbytes of Flash/EE data memory are configured as
1024 pages, each of four bytes. As with the other ADuC836
peripherals, the interface to this memory space is via a group of
registers mapped in the SFR space. A group of four data registers (EDATA1–A4) is used to hold the four bytes of data at each
page. The page is addressed via the two registers EADRH and
EADRL. Finally, ECON is an 8-bit control register that may be
written with one of nine Flash/EE memory access commands to
trigger various read, write, erase, and verify functions.
EDATA1 SFR
Using the Flash/EE Data Memory
Figure 20. Flash/EE Data Memory Control and Configuration
Table XIV. ECON—Flash/EE Memory Commands
Command Description
(Normal Mode) (Power-On Default)
Command Description
(ULOAD Mode)
01H
READ
Results in four bytes in the Flash/EE data memory,
addressed by the page address EADRH/L, being read
into EDATA 1 to 4.
Not Implemented. Use the MOVC instruction.
02H
WRITE
Results in four bytes in EDATA1–A4 being written to the
Flash/EE data memory, at the page address given by
EADRH/L (0  EADRH/L < 0400H)
Note: The four bytes in the page being addressed must
be pre-erased.
Results in bytes 0–255 of internal XRAM being written
to the 256 bytes of Flash/EE program memory at the
page address given by EADRH. (0  EADRH < E0H)
Note: The 256 bytes in the page being addressed must
be pre-erased.
03H
Reserved Command
Reserved Command
04H
VERIFY
Verifies if the data in EDATA1–4 is contained in the
page address given by EADRH/L. A subsequent read
of the ECON SFR will result in a 0 being read if the
verification is valid, or a nonzero value being read
to indicate an invalid verification.
Not Implemented. Use the MOVC and MOVX
instructions to verify the WRITE in software.
05H
ERASE PAGE
Results in the erase of the 4-bytes page of Flash/EE
data memory addressed by the page address EADRH/L
Results in the 64-byte page of Flash/EE program
memory, addressed by the byte address EADRH/L
being erased. EADRL can equal any of 64 locations
within the page. A new page starts whenever EADRL
is equal to 00H, 40H, 80H, or C0H.
06H
ERASE ALL
Results in the erase of entire four Kbytes of Flash/EE
data memory.
Results in the erase of the entire 56 Kbytes of ULOAD
Flash/EE program memory.
81H
READBYTE
Results in the byte in the Flash/EE data memory,
addressed by the byte address EADRH/L, being read
into EDATA1. (0  EADRH/L  0FFFH).
Not Implemented. Use the MOVC command.
82H
WRITEBYTE
Results in the byte in EDATA1 being written into
Flash/EE data memory, at the byte address EADRH/L.
Results in the byte in EDATA1 being written into
Flash/EE program memory at the byte address
EADRH/L (0  EADRH/L  DFFFH).
0FH
EXULOAD
Leaves the ECON instructions to operate on the
Flash/EE data memory.
Enters Normal mode, directing subsequent ECON
instructions to operate on the Flash/EE data memory.
F0H
ULOAD
Enters ULOAD mode, directing subsequent ECON
instructions to operate on the Flash/EE program memory.
Leaves the ECON instructions to operate on the Flash/EE
program memory.
ECON Value
–32–
REV. A
ADuC836
Programming the Flash/EE Data Memory
A user wishes to program F3H into the second byte on Page 03H
of the Flash/EE data memory space while preserving the other
three bytes already in this page.
A typical program of the Flash/EE Data array will involve:
1. Setting EADRH/L with the page address
2. Writing the data to be programmed to the EDATA1–4
3. Writing the ECON SFR with the appropriate command
Step 1: Set Up the Page Address
The two address registers, EADRH and EADRL, hold the high
byte address and the low byte address of the page to be addressed.
The assembly language to set up the address may appear as:
MOV EADRH,#0 ; Set Page Address Pointer
MOV EADRL,#03H
set to FFH, it is nonetheless good programming practice to
include an erase-all routine as part of any configuration/setup
code running on the ADuC836. An ERASE-ALL command
consists of writing 06H to the ECON SFR, which initiates an
erase of the 4-Kbyte Flash/EE array. This command coded in
8051 assembly would appear as:
MOV ECON,#06H ; Erase all Command
; 2 ms Duration
Flash/EE Memory Timing
Typical program and erase times for the ADuC836 are as follows:
Normal Mode (operating on Flash/EE data memory)
READPAGE (4 bytes)
WRITEPAGE (4 bytes)
VERIFYPAGE (4 bytes)
ERASEPAGE (4 bytes)
ERASEALL (4 Kbytes)
READBYTE (1 byte)
WRITEBYTE (1 byte)
Step 2: Set Up the EDATA Registers
The four values to be written into the page into the four SFRs
EDATA1–4. Since we do not know three of them, it is necessary
to read the current page and overwrite the second byte.
MOV ECON,#1 ; Read Page into EDATA1-4
MOV EDATA2,#0F3H ; Overwrite byte 2
ULOAD Mode (operating on Flash/EE program memory)
WRITEPAGE (256 bytes)
ERASEPAGE (64 bytes)
ERASEALL (56 Kbytes)
WRITEBYTE (1 byte)
Step 3: Program Page
A byte in the Flash/EE array can be programmed only if it has
previously been erased. To be more specific, a byte can only be
programmed if it already holds the value FFH. Because of the
Flash/EE architecture, this erase must happen at a page level.
Therefore, a minimum of four bytes (1 page) will be erased when
an erase command is initiated. Once the page is erased, we can
program the four bytes in-page and then perform a verification of
the data.
MOV ECON,#5 ; ERASE Page
MOV ECON,#2 ; WRITE Page
MOV ECON,#4 ; VERIFY Page
MOV A,ECON ; Check if ECON=0 (OK!)
JNZ ERROR
Note that although the four Kbytes of Flash/EE data memory
is shipped from the factory pre-erased, i.e., Byte locations
REV. A
– 5 machine cycles
– 380 s
– 5 machine cycles
– 2 ms
– 2 ms
– 3 machine cycles
– 200 s
– 15 ms
– 2 ms
– 2 ms
– 200 s
It should be noted that a given mode of operation is initiated as
soon as the command word is written to the ECON SFR. The
core microcontroller operation on the ADuC836 is idled until the
requested Program/Read or Erase mode is completed.
In practice, this means that even though the Flash/EE memory
mode of operation is typically initiated with a two-machine
cycle MOV instruction (to write to the ECON SFR), the next
instruction will not be executed until the Flash/EE operation is
complete. This means that the core will not respond to interrupt
requests until the Flash/EE operation is complete, although the
core peripheral functions like counter/timers will continue to
count and time as configured throughout this period.
–33–
ADuC836
DAC
The ADuC836 incorporates a 12-bit voltage output DAC
on-chip. It has a rail-to-rail voltage output buffer capable of driving
10 k/100 pF. It has two selectable ranges, 0 V to VREF (the internal band gap 2.5 V reference) and 0 V to AVDD. It can operate
in 12-bit or 8-bit mode. The DAC has a control register, DACCON,
and two data registers, DACH/L. The DAC output can be
programmed to appear at Pin 3 or Pin 12. It should be noted
that in 12-bit mode, the DAC voltage output will be updated
as soon as the DACL data SFR has been written; therefore, the
DAC data registers should be updated as DACH first, followed
by DACL. The 12-bit DAC data should be written into DACH/L
right-justified such that DACL contains the lower eight bits, and
the lower nibble of DACH contains the upper four bits.
Table XV. DACCON SFR Bit Designations
Bit
Name
Description
7
–––
Reserved for Future Use
6
–––
Reserved for Future Use
5
–––
Reserved for Future Use
4
DACPIN
DAC Output Pin Select.
Set by user to direct the DAC output to Pin 12 (P1.7/AIN4/DAC).
Cleared by user to direct the DAC output to Pin 3 (P1.2/DAC/IEXC1).
3
DAC8
DAC 8-bit Mode Bit.
Set by user to enable 8-bit DAC operation. In this mode, the 8 bits in DACL SFR are routed to the 8 MSBs
of the DAC, and the 4 LSBs of the DAC are set to zero.
Cleared by user to operate the DAC in its normal 12-bit mode of operation.
2
DACRN
DAC Output Range Bit.
Set by user to configure DAC range of 0 to AVDD.
Cleared by user to configure DAC range of 0 V to 2.5 V (VREF).
1
DACCLR
DAC Clear Bit.
Set to 1 by user to enable normal DAC operation.
Cleared to 0 by user to reset DAC data registers DACL/H to zero.
0
DACEN
DAC Enable Bit.
Set to 1 by user to enable normal DAC operation.
Cleared to 0 by user to power down the DAC.
DACH/L
DAC Data Registers
Function
SFR Address
DAC Data Registers, written by user to update the DAC output.
DACL (DAC Data Low Byte)
FBH
DACH (DAC Data High Byte) FCH
00H
Both Registers
No
Both Registers
Power-On Default Value
Bit Addressable
Using the D/A Converter
The on-chip D/A converter architecture consists of a resistor
string DAC followed by an output buffer amplifier, the functional
equivalent of which is illustrated in Figure 21.
AVDD
VREF
ADuC836
R
OUTPUT
BUFFER
R
12 DAC
R
HIGH-Z
DISABLE
(FROM MCU)
R
R
Figure 21. Resistor String DAC Functional Equivalent
Features of this architecture include inherent guaranteed monotonicity and excellent differential linearity. As illustrated in Figure 21,
the reference source for the DAC is user selectable in software. It
can be either AVDD or VREF. In 0-to-AVDD mode, the DAC output
transfer function spans from 0 V to the voltage at the AVDD pin.
In 0-to-VREF mode, the DAC output transfer function spans from
0 V to the internal VREF (2.5 V). The DAC output buffer amplifier
features a true rail-to-rail output stage implementation. This means
that, unloaded, each output is capable of swinging to within less than
100 mV of both AVDD and ground. Moreover, the DAC’s linearity specification (when driving a 10 k resistive load to ground)
is guaranteed through the full transfer function except codes 0
to 48 in 0-to-VREF mode and 0 to 100 and 3950 to 4095 in 0-toVDD mode.
Linearity degradation near ground and VDD is caused by saturation
of the output amplifier, and a general representation of its effects
(neglecting offset and gain error) is illustrated in Figure 22. The
dotted line in Figure 22 indicates the ideal transfer function, and
the solid line represents what the transfer function might look
like with endpoint nonlinearities due to saturation of the output
amplifier.
–34–
REV. A
ADuC836
4
VDD
VDD–50mV
DAC LOADED WITH 0FFFH
OUTPUT VOLTAGE – V
VDD–100mV
3
1
100mV
DAC LOADED WITH 0000H
50mV
0mV
0
FFFH
000H
Figure 22. Endpoint Nonlinearities Due to
Amplifier Saturation
Note that Figure 22 represents a transfer function in 0-to-VDD mode
only. In 0-to-VREF mode (with VREF < VDD), the lower nonlinearity
would be similar, but the upper portion of the transfer function
would follow the “ideal” line right to the end, showing no signs of
endpoint linearity errors.
The endpoint nonlinearities conceptually illustrated in Figure 22
get worse as a function of output loading. Most of the ADuC836
data sheet specifications assume a 10 k resistive load to ground
at the DAC output. As the output is forced to source or sink more
current, the nonlinear regions at the top or bottom (respectively)
of Figure 22 become larger. With larger current demands, this
can significantly limit output voltage swing. Figures 23 and 24
illustrate this behavior. It should be noted that the upper trace in
each of these figures is valid only for an output range selection of
0-to-AVDD. In 0-to-VREF mode, DAC loading will not cause high
side voltage drops as long as the reference voltage remains below
the upper trace in the corresponding figure. For example, if AVDD
= 3 V and VREF = 2.5 V, the high side voltage will not be affected by
loads less than 5 mA. But somewhere around 7 mA, the upper curve
in Figure 24 drops below 2.5 V (VREF), indicating that at these
higher currents, the output will not be capable of reaching VREF.
5
OUTPUT VOLTAGE – V
For larger loads, the current drive capability may not be sufficient
To increase the source and sink current capability of the DAC, an
external buffer should be added, as shown in Figure 25.
ADuC836
12
Figure 25. Buffering the DAC Output
The DAC output buffer also features a high impedance disable function. In the chip’s default power-on state, the DAC is disabled and
its output is in a high impedance state (or “three-state”) where
they remain inactive until enabled in software.
This means that if a zero output is desired during power-up or
power-down transient conditions, a pull-down resistor must be
added to each DAC output. Assuming this resistor is in place, the
DAC output will remain at ground potential whenever the DAC
is disabled.
3
2
1
DAC LOADED WITH 0000H
0
0
10
5
SOURCE/SINK CURRENT – mA
15
Figure 23. Source and Sink Current Capability
with VREF = AVDD = 5 V
REV. A
15
Figure 24. Source and Sink Current Capability with
VREF = VDD = 3 V
DAC LOADED WITH 0FFFH
4
10
5
SOURCE/SINK CURRENT – mA
0
–35–
ADuC836
PULSEWIDTH MODULATOR (PWM)
The PWM on the ADuC836 is a highly flexible PWM offering
programmable resolution and input clock, and can be configured
for any one of six different modes of operation. Two of these modes
allow the PWM to be configured as a - DAC with up to 16 bits
of resolution. A block diagram of the PWM is shown in Figure 26.
12.583MHz
PWMCLK
CLOCK
SELECT
32.768kHz
32.768kHz/15
16-BIT PWM COUNTER
Figure 26.
MODE
PWM
PWMCON (as described in Table XVI) controls the different
modes of operation of the PWM as well as the PWM clock frequency. PWM0H/L and PWM1H/L are the data registers that
determine the duty cycles of the PWM outputs at P1.0 and P1.1.
To use the PWM user software, first write to PWMCON to select
the PWM mode of operation and the PWM input clock. Writing
to PWMCON also resets the PWM counter. In any of the 16-bit
modes of operation (modes 1, 3, 4, 6), user software should write
to the PWM0L or PWM1L SFRs first. This value is written to a
hidden SFR. Writing to the PWM0H or PWM1H SFRs updates
both the PWMxH and the PWMxL SFRs but does not change
the outputs until the end of the PWM cycle in progress. The
values written to these 16-bit registers are then used in the next
PWM cycle.
PROGRAMMABLE
DIVIDER
P1.0
COMPARE
The PWM uses five SFRs: the control SFR, PWMCON, and
four data SFRs: PWM0H, PWM0L, PWM1H, and PWM1L.
P1.1
PWM1H/L
PWM0H/L
Block
Diagram
PWMCON
PWM Control SFR
SFR Address
Power-On Default Value
Bit Addressable
AEH
00H
No
Table XVI. PWMCON SFR Bit Designations
Bit
Name
Description
7
–––
Reserved for Future Use
6
MD2
PWM Mode Bits
5
MD1
The MD2/1/0 bits choose the PWM mode as follows:
4
MD0
MD2
0
0
0
0
1
1
1
1
3
CDIV1
PWM Clock Divider.
2
CDIV0
Scale the clock source for the PWM counter as follows:
CDIV1
0
0
1
1
MD1
0
0
1
1
0
0
1
1
CDIV0
0
1
0
1
MD0
0
1
0
1
0
1
0
1
Mode
Mode 0: PWM Disabled
Mode 1: Single Variable Resolution PWM
Mode 2: Twin 8-bit PWM
Mode 3: Twin 16-bit PWM
Mode 4: Dual NRZ 16-bit - DAC
Mode 5: Dual 8-bit PWM
Mode 6: Dual RZ 16-bit - DAC
Reserved for Future Use
Description
PWM Counter = Selected Clock/1
PWM Counter = Selected Clock 4
PWM Counter = Selected Clock/16
PWM Counter = Selected Clock/64
1
CSEL1
PWM Clock Divider.
0
CSEL0
Select the clock source for the PWM as follows:
CSEL1
0
0
1
1
CSEL0
0
1
0
1
Description
PWM Clock = fXTAL/15
PWM Clock = fXTAL
PWM Clock = External Input at P3.4/T0/PWMCLK
PWM Clock = fVCO (12.58 MHz)
–36–
REV. A
ADuC836
PWM MODES OF OPERATION
Mode 0: PWM Disabled
PWM1L
PWM COUNTER
The PWM is disabled, allowing P1.0 and P1.1 to be used as normal.
PWM0H
Mode 1: Single Variable Resolution PWM
PWM0L
In Mode 1, both the pulse length and the cycle time (period) are
programmable in user code, allowing the resolution of the PWM
to be variable.
PWM1H
0
P1.0
PWM1H/L sets the period of the output waveform. Reducing
PWM1H/L reduces the resolution of the PWM output but
increases the maximum output rate of the PWM (e.g., setting
PWM1H/L to 65536 gives a 16-bit PWM with a maximum
output rate of 192 Hz (12.583 MHz/65536). Setting PWM1H/L
to 4096 gives a 12-bit PWM with a maximum output rate of
3072 Hz (12.583 MHz/4096)).
P1.1
Figure 28. PWM Mode 2
Mode 3: Twin 16-Bit PWM
In Mode 3, the PWM counter is fixed to count from 0 to 65536,
giving a fixed 16-bit PWM. Operating from the 12.58 MHz core
clock results in a PWM output rate of 192 Hz. The duty cycle of the
PWM outputs at P1.0 and P1.1 is independently programmable.
PWM0H/L sets the duty cycle of the PWM output waveform, as
shown in Figure 27.
PWM1H/L
PWM COUNTER
As in Figure 29, while the PWM counter is less than PWM0H/L,
the output of PWM0 (P1.0) is high. Once the PWM counter
equals PWM0H/L, PWM0 (P1.0) goes low and remains low until
the PWM counter rolls over.
PWM0H/L
Similarly, while the PWM counter is less than PWM1H/L, the
output of PWM1 (P1.1) is high. Once the PWM counter equals
PWM1H/L, PWM1 (P1.1) goes low and remains low until the
PWM counter rolls over.
0
P1.0
In this mode, both PWM outputs are synchronized (i.e., once the
PWM counter rolls over to 0, both PWM0 (P1.0) and PWM1
(P1.1) will go high).
Figure 27. PWM in Mode 1
Mode 2: Twin 8-Bit PWM
In Mode 2, the duty cycle of the PWM outputs and the resolution
of the PWM outputs are both programmable. The maximum
resolution of the PWM output is eight bits.
65536
PWM COUNTER
PWM1H/L
PWM1L sets the period for both PWM outputs. Typically this will
be set to 255 (FFH) to give an 8-bit PWM, although it is possible
to reduce this as necessary. A value of 100 could be loaded here
to give a percentage PWM (i.e., the PWM is accurate to 1%).
The outputs of the PWM at P1.0 and P1.1 are shown in Figure 28.
As can be seen, the output of PWM0 (P1.0) goes low when the
PWM counter equals PWM0L. The output of PWM1 (P1.1)
goes high when the PWM counter equals PWM1H and goes low
again when the PWM counter equals PWM0H. Setting PWM1H
to 0 ensures that both PWM outputs start simultaneously.
REV. A
PWM0H/L
0
P1.0
P1.1
Figure 29. PWM Mode 3
–37–
ADuC836
Mode 4: Dual NRZ 16-Bit - DAC
PWM1L
PWM COUNTERS
Mode 4 provides a high speed PWM output similar to that of a
- DAC. Typically, this mode will be used with the PWM clock
equal to 12.58 MHz.
PWM1H
PWM0L
In this mode, P1.0 and P1.1 are updated every PWM clock
(80 ns in the case of 12.58 MHz). Over any 65536 cycles (16-bit
PWM), PWM0 (P1.0) is high for PWM0H/L cycles and low for
(65536 – PWM0H/L) cycles. Similarly, PWM1 (P1.1) is high for
PWM1H/L cycles and low for (65536 – PWM1H/L) cycles.
If PWM1H is set to 4010H (slightly above one quarter of FS),
then typically P1.1 will be low for three clocks and high for one
clock (each clock is approximately 80 ns). Over every 65536
clocks, the PWM will compromise for the fact that the output
should be slightly above one quarter of full scale by having a high
cycle followed by only two low cycles.
PWM0H/L = C000H
CARRY OUT AT P1.0
16-BIT
16-BIT
16-BIT
12.583MHz
0
1
1
1
0
1
1
80s
LATCH
16-BIT
16-BIT
0
0
CARRY OUT AT P1.1
0
1
0
0
0
16-BIT
80s
PWM1H/L = 4000H
Figure 30. PWM Mode 4
For faster DAC outputs (at lower resolution), write 0s to the
LSBs that are not required with a 1 in the LSB position. If, for
example, only 12-bit performance is required, write 0001 to the
4 LSBs. This means that a 12-bit accurate - DAC output can
occur at 3 kHz. Similarly, writing 00000001 to the 8 LSBs gives
an 8-bit accurate - DAC output at 49 kHz.
PWM0H
0
P1.0
P1.1
Figure 31. PWM Mode 5
Mode 6: Dual RZ 16-Bit - DAC
Mode 6 provides a high speed PWM output similar to that of a
- DAC. Mode 6 operates very similarly to Mode 4. However,
the key difference is that Mode 6 provides return to zero (RZ)
- DAC output. Mode 4 provides non-return-to-zero -
DAC outputs. The RZ mode ensures that any difference in the
rise and fall times will not affect the - DAC INL. However,
the RZ Mode halves the dynamic range of the - DAC outputs
from 0AVDD to 0AVDD/2. For best results, this mode should
be used with a PWM clock divider of 4.
If PWM1H is set to 4010H (slightly above one quarter of FS)
then P1.1 will typically be low for three full clocks (3  80 ns),
high for half a clock (40 ns) and then low again for half a clock
(40 ns) before repeating itself. Over every 65536 clocks, the
PWM will compromise for the fact that the output should be
slightly above one quarter of full scale by leaving the output high
for two half clocks in four every so often.
For faster DAC outputs (at lower resolution), write 0s to the
LSBs that are not required with a 1 in the LSB position. If, for
example, only 12-bit performance is required, write 0001 to the
4 LSBs. This means that a 12-bit accurate - DAC output can
occur at 3 kHz. Similarly, writing 00000001 to the 8 LSBs gives
an 8-bit accurate - DAC output at 49 kHz.
PWM0H/L = C000H
CARRY OUT AT P1.0
16-BIT
Mode 5: Dual 8-Bit PWM
16-BIT
16-BIT
In Mode 5, the duty cycle of the PWM outputs and the resolution
of the PWM outputs are individually programmable. The maximum resolution of the PWM output is 8 bits.
3.146MHz
The output resolution is set by the PWM1L and PWM1H SFRs
for the P1.0 and P1.1 outputs, respectively. PWM0L and
PWM0H set the duty cycles of the PWM outputs at P1.0 and
P1.1, respectively. Both PWMs have the same clock source and
clock divider.
16-BIT
0 1
1
1
0 1
1
318s
LATCH
16-BIT
CARRY OUT AT P1.1
0
0
0 1
0
0
0
16-BIT
318s
PWM1H/L = 4000H
Figure 32. PWM Mode 6
–38–
REV. A
ADuC836
ON-CHIP PLL
The ADuC836 is intended for use with a 32.768 kHz watch
crystal. A PLL locks onto a multiple (384) of this to provide a
stable 12.582912 MHz clock for the system. The core can
operate at this frequency, or at binary submultiples of it, to allow
power saving in cases where maximum core performance is not
PLLCON
PLL Control Register
SFR Address
Power-On Default Value
Bit Addressable
D7H
03H
No
required. The default core clock is the PLL clock divided by
8 or 1.572864 MHz. The ADC clocks are also derived from the
PLL clock, with the modulator rate being the same as the crystal
oscillator frequency. This choice of frequencies ensures that the
modulators and the core will be synchronous, regardless of the
core clock rate. The PLL control register is PLLCON.
Table XVII. PLLCON SFR Bit Designations
Bit
Name
Description
7
OSC_PD
Oscillator Power-Down Bit.
Set by user to halt the 32 kHz oscillator in Power-Down mode.
Cleared by user to enable the 32 kHz oscillator in Power-Down mode.
This feature allows the TIC to continue counting even in Power-Down mode.
6
LOCK
PLL Lock Bit. This is a read-only bit.
Set automatically at power-on to indicate the PLL loop is correctly tracking the crystal clock. After
power-down, this bit can be polled to wait for the PLL to lock.
Cleared automatically at power-on to indicate the PLL is not correctly tracking the crystal clock. This may
be due to the absence of a crystal clock or an external crystal at power-on. In this mode, the PLL output
can be 12.58 MHz ± 20%. After the ADuC836 wakes up from power-down, user code may poll this bit
to wait for the PLL to lock. If LOCK = 0, then the PLL is not locked.
5
–––
Reserved for Future Use. Should be written with 0.
4
LTEA
Reading this bit returns the state of the external EA pin latched at reset or power-on.
3
FINT
Fast Interrupt Response Bit.
Set by user enabling the response to any interrupt to be executed at the fastest core clock frequency,
regardless of the configuration of the CD2–0 bits (see below). After user code has returned from an interrupt,
the core resumes code execution at the core clock selected by the CD2–0 bits. Cleared by user to disable
the fast interrupt response feature.
2
CD2
CPU (Core Clock) Divider Bits.
1
CD1
This number determines the frequency at which the microcontroller core will operate.
0
CD0
CD2
0
0
0
0
1
1
1
1
REV. A
CD1
0
0
1
1
0
0
1
1
CD0
0
1
0
1
0
1
0
1
Core Clock Frequency (MHz)
12.582912
6.291456
3.145728
1.572864 (Default Core Clock Frequency)
0.786432
0.393216
0.196608
0.098304
–39–
ADuC836
TIME INTERVAL COUNTER (WAKE-UP/RTC TIMER)
If the ADuC836 is in Power-Down mode, again with TIC interrupt enabled, the TII bit will wake up the device and resume
code execution by vectoring directly to the TIC interrupt service
vector address at 0053H. The TIC-related SFRs are described in
Table XVIII with a block diagram of the TIC shown in Figure 33.
A time interval counter (TIC) is provided on-chip for:
 Periodically waking up the part from power-down
 Implementing a real-time clock
 Counting longer intervals than the standard 8051 compatible
timers are capable of
TCEN
The TIC is capable of timeout intervals ranging from 1/128th
second to 255 hours. Furthermore, this counter is clocked by the
crystal oscillator rather than the by PLL, and thus has the ability to
remain active in Power-Down mode and time long power-down
intervals. This has obvious applications for remote battery-powered
sensors where regular widely, spaced readings are required.
32.768kHz EXTERNAL CRYSTAL
ITS0, 1
8-BIT
PRESCALER
HUNDREDTHS COUNTER
HTHSEC
The TIC counter can easily be used to generate a real-time
clock. The hardware will count in seconds, minutes, and hours;
however, user software will have to count in days, months, and
years. The current time can be written to the timebase SFRs
(HTHSEC, SEC, MIN, and HOUR) while TCEN is low. When
the RTC timer is enabled (TCEN is set), the TCEN bit itself and
the HTHSEC, SEC, MIN, and HOUR Registers are not reset to
00H after a hardware or watchdog timer reset. This is to prevent
the need to recalibrate the real-time clock after a reset. However,
these registers will be reset to 00H after a power cycle (independent of TCEN) or after any reset if TCEN is clear.
SECOND COUNTER
SEC
INTERVAL
TIMEBASE
SELECTION
MUX
TIEN
MINUTE COUNTER
MIN
HOUR COUNTER
HOUR
Six SFRs are associated with the time interval counter, TIMECON
being its control register. Depending on the configuration of the
IT0 and IT1 bits in TIMECON, the selected time counter register
overflow will clock the interval counter. When this counter is equal
to the time interval value loaded in the INTVAL SFR, the TII
bit (TIMECON.2) is set and generates an interrupt if enabled.
(See IEIP2 SFR description under the Interrupt System section.)
INTERVAL TIMEOUT
TIME INTERVAL COUNTER INTERRUPT
8-BIT
INTERVAL COUNTER
EQUAL?
INTVAL SFR
Figure 33. TIC, Simplified Block Diagram
Table XVIII. TIMECON SFR Bit Designations
Bit
Name
Description
7
6
5
4
–––
–––
ITS1
ITS0
3
STI
2
TII
1
TIEN
0
TCEN
Reserved for Future Use
Reserved for Future Use. For future product code compatibility, this bit should be written as a 1.
Interval Timebase Selection Bits.
Written by user to determine the interval counter update rate.
ITS1
ITS0
Interval Timebase
0
0
1/128 Second
0
1
Seconds
1
0
Minutes
1
1
Hours
Single Time Interval Bit.
Set by user to generate a single interval timeout. If set, a timeout will clear the TIEN bit.
Cleared by user to allow the interval counter to be automatically reloaded and start counting again at each interval
timeout.
TIC Interrupt Bit.
Set when the 8-bit interval counter matches the value in the INTVAL SFR.
Cleared by user software.
Time Interval Enable Bit.
Set by user to enable the 8-bit time interval counter.
Cleared by user to disable and clear the contents of the 8-bit interval counter. To ensure that the 8-bit interval
counter is cleared, TIEN must be held low for at least 30.5 s (32 kHz).
Time Clock Enable Bit.
Set by user to enable the time clock to the time interval counters.
Cleared by user to disable the 32 kHz clock to the TIC and clear the 8-bit prescaler and the HTHSEC, SEC,
MIN, and HOURS SFRs. To ensure that these registers are cleared, TCEN must be held low for at least 30.5 s
(32 kHz). The time registers (HTHSEC, SEC, MIN, and HOUR) can be written only while TCEN is low.
–40–
REV. A
ADuC836
INTVAL
User Time Interval Select Register
Function
SFR Address
Power-On Default Value
Reset Default Value
Bit Addressable
Valid Value
User code writes the required time interval to this register. When the 8-bit interval counter is equal
to the time interval value loaded in the INTVAL SFR, the TII bit (TIMECON.2) is set and generates
an interrupt if enabled. (See IEIP2 SFR description under the Interrupt System section.)
A6H
00H
00H
No
0 to 255 decimal
HTHSEC
Hundredths Seconds Time Register
Function
SFR Address
Power-On Default Value
Reset Default Value
Bit Addressable
Valid Value
This register is incremented in 1/128 second intervals once TCEN in TIMECON is active.
The HTHSEC SFR counts from 0 to 127 before rolling over to increment the SEC time register.
A2H
00H
00H if TCEN = 0, previous value before reset if TCEN = 1
No
0 to 127 decimal
SEC
Seconds Time Register
Function
SFR Address
Power-On Default Value
Reset Default Value
Bit Addressable
Valid Value
This register is incremented in 1-second intervals once TCEN in TIMECON is active.
The SEC SFR counts from 0 to 59 before rolling over to increment the MIN time register.
A3H
00H
00H if TCEN = 0, previous value before reset if TCEN = 1
No
0 to 59 decimal
MIN
Minutes Time Register
Function
SFR Address
Power-On Default Value
Reset Default Value
Bit Addressable
Valid Value
This register is incremented in 1-minute intervals once TCEN in TIMECON is active.
The MIN counts from 0 to 59 before rolling over to increment the HOUR time register.
A4H
00H
00H if TCEN = 0, previous value before reset if TCEN = 1
No
0 to 59 decimal
HOUR
Hours Time Register
Function
This register is incremented in 1-hour intervals once TCEN in TIMECON is active. The HOUR SFR
counts from 0 to 23 before rolling over to 0.
A5H
00H
00H if TCEN = 0, previous value before reset if TCEN = 1
No
0 to 23 decimal
SFR Address
Power-On Default Value
Reset Default Value
Bit Addressable
Valid Value
REV. A
–41–
ADuC836
WATCHDOG TIMER
amount of time (see PRE3–0 bits in WDCON). The watchdog
timer itself is a 16-bit counter that is clocked at 32.768 kHz. The
watchdog timeout interval can be adjusted via the PRE3–0 bits in
WDCON. Full control and status of the watchdog timer function
can be controlled via the Watchdog Timer Control SFR (WDCON).
The WDCON SFR can only be written by user software if the
double write sequence described in WDWR below is initiated on
every write access to the WDCON SFR.
The purpose of the watchdog timer is to generate a device reset
or interrupt within a reasonable amount of time if the ADuC836
enters an erroneous state, possibly due to a programming error,
electrical noise, or RFI. The watchdog function can be disabled
by clearing the WDE (Watchdog Enable) bit in the Watchdog
Control (WDCON) SFR. When enabled, the watchdog circuit will
generate a system reset or interrupt (WDS) if the user program
fails to set the watchdog (WDE) bit within a predetermined
WDCON
SFR Address
Power-On Default Value
Bit Addressable
Watchdog Timer Control Register
C0H
10H
Yes
Table XIX. WDCON SFR Bit Designations
Bit
Name
Description
7
PRE3
Watchdog Timer Prescale Bits.
6
PRE2
The Watchdog timeout period is given by the equation tWD = (2PRE  (29/fPLL))
5
PRE1
(0  PRE  7; fPLL = 32.768 kHz)
4
PRE0
3
WDIR
Watchdog Interrupt Response Enable Bit. If this bit is set by the user, the watchdog will generate an interrupt
response instead of a system reset when the watchdog timeout period has expired. This interrupt is not disabled by
the CLR EA instruction, and it is also a fixed, high priority interrupt. If the watchdog is not being used to monitor
the system, it can alternatively be used as a timer. The prescaler is used to set the timeout period in which an
interrupt will be generated. (See also Note 1, Table XXXIX in the Interrupt System section.)
2
WDS
Watchdog Status Bit.
Set by the watchdog controller to indicate that a watchdog timeout has occurred.
Cleared by writing a 0 or by an external hardware reset. It is not cleared by a watchdog reset.
1
WDE
Watchdog Enable Bit.
Set by user to enable the watchdog and clear its counters. If a 1 is not written to this bit within the watchdog timeout
period, the watchdog will generate a reset or interrupt, depending on WDIR.
Cleared under the following conditions: User writes 0, watchdog reset (WDIR = 0); hardware reset; PSM interrupt.
0
WDWR
Watchdog Write Enable Bit.
To write data into the WDCON SFR involves a double instruction sequence. The WDWR bit must be set and the
very next instruction must be a write instruction to the WDCON SFR. For example:
CLR
EA
; disable interrupts while writing
; to WDT
SETB
WDWR
; allow write to WDCON
MOV
WDCON, #72h ; enable WDT for 2.0s timeout
SETB
EA
; enable interrupts again (if rqd)
PRE3 PRE2
0
0
0
0
0
0
0
0
0
1
0
1
0
1
0
1
1
0
PRE3–0 > 1001
PRE1
0
0
1
1
0
0
1
1
0
PRE0
0
1
0
1
0
1
0
1
0
Timeout
Period (ms)
15.6
31.2
62.5
125
250
500
1000
2000
0.0
–42–
Action
Reset or Interrupt
Reset or Interrupt
Reset or Interrupt
Reset or Interrupt
Reset or Interrupt
Reset or Interrupt
Reset or Interrupt
Reset or Interrupt
Immediate Reset
Reserved
REV. A
ADuC836
POWER SUPPLY MONITOR
As its name suggests, the Power Supply Monitor, once enabled,
monitors both supplies (AVDD or DVDD) on the ADuC836. It will
indicate when any of the supply pins drops below one of four
user-selectable voltage trip points from 2.63 V to 4.63 V. For correct operation of the Power Supply Monitor function, AVDD must
be equal to or greater than 2.7 V. Monitor function is controlled via
the PSMCON SFR. If enabled via the IEIP2 SFR, the monitor
PSMCON
Power Supply Monitor Control Register
SFR Address
Power-On Default Value
Bit Addressable
DFH
DEH
No
will interrupt the core using the PSMI bit in the PSMCON SFR.
This bit will not be cleared until the failing power supply has
returned above the trip point for at least 250 ms. This monitor
function allows the user to save working registers to avoid possible
data loss due to the low supply condition, and also ensures that
normal code execution will not resume until a safe supply level
has been well established. The supply monitor is also protected
against spurious glitches triggering the interrupt circuit.
Table XX. PSMCON SFR Bit Designations
Bit
Name
Description
7
CMPD
DVDD Comparator Bit.
This is a read-only bit and directly reflects the state of the DVDD comparator.
Read 1 indicates the DVDD supply is above its selected trip point.
Read 0 indicates the DVDD supply is below its selected trip point.
6
CMPA
AVDD Comparator Bit.
This is a read-only bit and directly reflects the state of the AVDD comparator.
Read 1 indicates the AVDD supply is above its selected trip point.
Read 0 indicates the AVDD supply is below its selected trip point.
5
PSMI
Power Supply Monitor Interrupt Bit.
This bit will be set high by the MicroConverter if either CMPA or CMPD are low, indicating low analog or digital
supply. The PSMI Bit can be used to interrupt the processor. Once CMPD and/or CMPA return (and remain)
high, a 250 ms counter is started. When this counter times out, the PSMI interrupt is cleared. PSMI can also be
written by the user. However, if either comparator output is low, it is not possible for the user to clear PSMI.
4
TPD1
DVDD Trip Point Selection Bits.
3
TPD0
These bits select the DVDD trip point voltage as follows:
TPD1
TPD0
Selected DVDD Trip Point (V)
0
0
4.63
0
1
3.08
1
0
2.93
1
1
2.63
2
TPA1
AVDD Trip Point Selection Bits.
1
TPA0
These bits select the AVDD trip point voltage as follows:
TPA1
TPA0
Selected AVDD Trip Point (V)
0
0
4.63
0
1
3.08
1
0
2.93
1
1
2.63
0
PSMEN
Power Supply Monitor Enable Bit.
Set to 1 by the user to enable the Power Supply Monitor Circuit.
Cleared to 0 by the user to disable the Power Supply Monitor Circuit.
REV. A
–43–
ADuC836
SERIAL PERIPHERAL INTERFACE
MISO (Master In, Slave Out Data I/O Pin), Pin 14
The ADuC836 integrates a complete hardware Serial Peripheral
Interface (SPI) interface on-chip. SPI is an industry-standard
synchronous serial interface that allows eight bits of data to be
synchronously transmitted and received simultaneously, i.e., fullduplex. It should be noted that the SPI pins SCLOCK and MOSI
are multiplexed with the I2C pins SCLOCK and SDATA. The pins
are controlled via the I2CCON SFR only if SPE is clear. SPI can
be configured for master or slave operation and typically consists of
four pins:
The MISO (master in slave out) pin is configured as an input line
in Master mode and an output line in Slave mode. The MISO
line on the master (data in) should be connected to the MISO
line in the slave device (data out). The data is transferred as bytewide (8-bit) serial data, MSB first.
SCLOCK (Serial Clock I/O Pin), Pin 26
The master clock (SCLOCK) is used to synchronize the data
being transmitted and received through the MOSI and MISO
data lines. A single data bit is transmitted and received in each
SCLOCK period. Therefore, a byte is transmitted/received after
eight SCLOCK periods. The SCLOCK pin is configured as an
output in master mode and as an input in Slave mode. In Master
mode, the bit rate, polarity, and phase of the clock are controlled
by the CPOL, CPHA, SPR0, and SPR1 bits in the SPICON SFR
(see Table XXI). In Slave mode, the SPICON register will have
to be configured with the phase and polarity (CPHA and CPOL)
as the master, as for both Master and Slave modes the data is
transmitted on one edge of the SCLOCK signal and sampled on
the other.
MOSI (Master Out, Slave In Pin), Pin 27
The MOSI (master out slave in) pin is configured as an output
line in Master mode and an input line in Slave mode. The MOSI
line on the master (data out) should be connected to the MOSI
line in the slave device (data in). The data is transferred as bytewide (8-bit) serial data, MSB first.
SS (Slave Select Input Pin), Pin 13
The Slave Select (SS) input pin is only used when the ADuC836
is configured in SPI Slave mode. This line is active low. Data is
only received or transmitted in Slave mode when the SS pin is low,
allowing the ADuC836 to be used in single master, multislave SPI
configurations. If CPHA = 1, the SS input may be permanently
pulled low. With CPHA = 0, the SS input must be driven low
before the first bit in a byte wide transmission or reception and
return high again after the last bit in that byte-wide transmission or
reception. In SPI Slave mode, the logic level on the external SS pin
(Pin 13) can be read via the SPR0 bit in the SPICON SFR.
The following SFR registers are used to control the SPI interface.
Table XXI. SPICON SFR Bit Designations
Bit
Name
Description
7
ISPI
SPI Interrupt Bit.
Set by MicroConverter at the end of each SPI transfer.
Cleared directly by user code or indirectly by reading the SPIDAT SFR.
6
WCOL
Write Collision Error Bit.
Set by MicroConverter if SPIDAT is written to while an SPI transfer is in progress.
Cleared by user code.
5
SPE
SPI Interface Enable Bit.
Set by user to enable the SPI interface.
Cleared by user to enable the I2C interface.
4
SPIM
SPI Master/Slave Mode Select Bit.
Set by user to enable Master mode operation (SCLOCK is an output).
Cleared by user to enable Slave mode operation (SCLOCK is an input).
3
CPOL*
Clock Polarity Select Bit.
Set by user if SCLOCK idles high.
Cleared by user if SCLOCK idles low.
2
CPHA*
Clock Phase Select Bit.
Set by user if leading SCLOCK edge is to transmit data.
Cleared by user if trailing SCLOCK edge is to transmit data.
1
SPR1
SPI Bit Rate Select Bits.
0
SPR0
These bits select the SCLOCK rate (bitrate) in Master mode as follows:
SPR1
SPR0
Selected Bit Rate
0
0
fCORE/2
0
1
fCORE/4
1
0
fCORE/8
1
1
fCORE/16
In SPI Slave mode, i.e., SPIM = 0, the logic level on the external SS pin (Pin 13), can be read via the SPR0 bit.
*The CPOL and CPHA bits should both contain the same values for master and slave devices.
–44–
REV. A
ADuC836
SPIDAT
SPI Data Register
Function
The SPIDAT SFR is written by the user to transmit data over the SPI interface or read by user code to read
data just received by the SPI interface.
F7H
00H
No
SFR Address
Power-On Default Value
Bit Addressable
Depending on the configuration of the bits in the SPICON SFR
shown in Table XXI, the ADuC836 SPI interface will transmit
or receive data in a number of possible modes. Figure 34 shows
all possible ADuC836 SPI configurations and the timing relationships and synchronization between the signals involved. Also
shown in this figure is the SPI Interrupt bit (ISPI) and how it is
triggered at the end of each byte-wide communication.
SCLOCK
(CPOL = 1)
SCLOCK
(CPOL = 0)
SS
SAMPLE INPUT
(CPHA = 1)
DATA OUTPUT
? MSB BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 LSB
SPI Interface—Master Mode
In Master mode, the SCLOCK pin is always an output and generates a burst of eight clocks whenever user code writes to the
SPIDAT Register. The SCLOCK bit rate is determined by SPR0
and SPR1 in SPICON. It should also be noted that the SS pin
is not used in Master mode. If the ADuC836 needs to assert
the SS pin on an external slave device, a port digital output pin
should be used.
In Master mode, a byte transmission or reception is initiated
by a write to SPIDAT. Eight clock periods are generated via
the SCLOCK pin and the SPIDAT byte being transmitted via
MOSI. With each SCLOCK period, a data bit is also sampled
via MISO. After eight clocks, the transmitted byte will have been
completely transmitted and the input byte will be waiting in the
input shift register. The ISPI flag will be set automatically and an
interrupt will occur if enabled. The value in the shift register will
be latched into SPIDAT.
SPI Interface—Slave Mode
ISPI FLAG
SAMPLE INPUT
(CPHA = 0)
DATA OUTPUT
MSB BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 LSB ?
ISPI FLAG
Figure 34. SPI Timing, All Modes
REV. A
In Slave mode, the SCLOCK is an input. The SS pin must also
be driven low externally during the byte communication. Transmission is also initiated by a write to SPIDAT. In Slave mode,
a data bit is transmitted via MISO and a data bit is received via
MOSI through each input SCLOCK period. After eight clocks,
the transmitted byte will have been completely transmitted and
the input byte will be waiting in the input shift register. The ISPI
flag will be set automatically and an interrupt will occur if enabled.
The value in the shift register will be latched into SPIDAT only
when the transmission/reception of a byte has been completed.
The end of transmission occurs after the eighth clock has been
received, if CPHA = 1 or when SS returns high if CPHA = 0.
–45–
ADuC836
I2C SERIAL INTERFACE
The ADuC836 supports a fully licensed* I2C serial interface. The
I2C interface is implemented as a full hardware slave and software master. SDATA (Pin 27) is the data I/O pin and SCLOCK
(Pin 26) is the serial clock. These two pins are shared with the
MOSI and SCLOCK pins of the on-chip SPI interface. Therefore
I2CCON
SFR Address
Power-On Default Value
Bit Addressable
the user can enable only one interface or the other at any given
time (see SPE in Table XXI). Application Note uC001 describes
the operation of this interface as implemented and is available from
the MicroConverter website at: www.analog.com/microconverter.
Three SFRs are used to control the I2C interface. These are
described below.
I2C Control Register
E8H
00H
Yes
Table XXII. I2CCON SFR Bit Designations
Bit
Name
Description
7
MDO
I2C Software Master Data Output Bit (Master Mode Only).
This data bit is used to implement a master I2C transmitter interface in software. Data written to this bit will
be output on the SDATA pin if the data output enable (MDE) bit is set.
6
MDE
I2C Software Master Data Output Enable Bit (Master Mode Only).
Set by user to enable the SDATA pin as an output (Tx).
Cleared by user to enable SDATA pin as an input (Rx).
5
MCO
I2C Software Master Clock Output Bit (Master Mode Only).
This data bit is used to implement a master I2C transmitter interface in software. Data written to this bit will
be output on the SCLOCK pin.
4
MDI
I2C Software Master Data Input Bit (Master Mode Only).
This data bit is used to implement a master I2C receiver interface in software. Data on the SDATA pin is
latched into this bit on SCLOCK if the data output enable (MDE) bit is 0.
3
I2CM
I2C Master/Slave Mode Bit.
Set by user to enable I2C software Master mode.
Cleared by user to enable I2C hardware Slave mode.
2
I2CRS
I2C Reset Bit (Slave Mode Only).
Set by user to reset the I2C interface.
Cleared by user code for normal I2C operation.
1
I2CTX
I2C Direction Transfer Bit (Slave Mode Only).
Set by MicroConverter if the interface is transmitting.
Cleared by the MicroConverter if the interface is receiving.
0
I2CI
I2C Interrupt Bit (Slave Mode Only).
Set by the MicroConverter after a byte has been transmitted or received.
Cleared automatically when the user code reads the I2CDAT SFR (see I2CDAT below).
I2CADD
I2C Address Register
SFR Address
Power-On Default Value
Bit Addressable
Holds the I2C peripheral address for the part. It may be overwritten by the user code. Application Note uC001
at www.analog.com/microconverter describes the format of the I2C standard 7-bit address in detail.
9BH
55H
No
I2CDAT
I2C Data Register
Function
Function
SFR Address
Power-On Default Value
Bit Addressable
The I2CDAT SFR is written by the user to transmit data over the I2C interface or read by user code to read
data just received by the I2C interface. Accessing I2CDAT automatically clears any pending I2C interrupt
and the I2CI bit in the I2CCON SFR. User software should access I2CDAT only once per interrupt cycle.
9AH
00H
No
*Purchase of licensed I2C components of Analog Devices or one of its sublicensed associated companies conveys a license for the purchaser under the Philips I2C
Patent Rights to use these components in an I2C system provided that the system conforms to the I2C Standard Specification as defined by Philips.
–46–
REV. A
ADuC836
The main features of the MicroConverter I2C interface are:



Once enabled in I2C Slave mode, the slave controller waits for
a START condition. If the ADuC836 detects a valid start condition followed by a valid address, and by the R/W bit, the I2CI
interrupt bit will be automatically set by hardware.
Only two bus lines are required: a serial data line (SDATA)
and a serial clock line (SCLOCK).
An I2C master can communicate with multiple slave devices.
Because each slave device has a unique 7-bit address, single
master/slave relationships can exist at all times even in a
multislave environment (Figure 35).
On-chip filtering rejects <50 ns spikes on the SDATA and
SCLOCK lines to preserve data integrity.
The I2C peripheral will only generate a core interrupt if the user
has preconfigured the I2C interrupt enable bit in the IEIP2 SFR
as well as the global interrupt Bit EA in the IE SFR, i.e.,
; Enabling I2C Interrupts for the ADuC836
MOV IEIP2,#01h ; enable I2C interrupt
SETB EA
DVDD
I2C
MASTER
On the ADuC836, an auto clear of the I2CI bit is implemented
so this bit is cleared automatically on a read or write access to the
I2CDAT SFR.
I2C
SLAVE #1
MOV I2CDAT, A ; I2CI auto-cleared
MOV A, I2CDAT ; I2CI auto-cleared
If for any reason the user tries to clear the interrupt more than
once, i.e., access the data SFR more than once per interrupt,
then the I2C controller will halt. The interface will then have to
be reset using the I2CRS bit.
I2C
SLAVE #2
Figure 35. Typical I 2C System
Software Master Mode
The ADuC836 can be used as an I2C master device by configuring
the I2C peripheral in Master mode and writing software to output
the data bit by bit, which is referred to as a software master. Master
mode is enabled by setting the I2CM bit in the I2CCON register.
The user can choose to poll the I2CI bit or enable the interrupt.
In the case of the interrupt, the PC counter will vector to 003BH
at the end of each complete byte. For the first byte when the user
gets to the I2CI ISR, the 7-bit address and the R/W bit will appear
in the I2CDAT SFR.
To transmit data on the SDATA line, MDE must be set to enable
the output driver on the SDATA pin. If MDE is set, the SDATA
pin will be pulled high or low depending on whether the MDO
bit is set or cleared. MCO controls the SCLOCK pin and is
always configured as an output in Master mode. In Master mode,
the SCLOCK pin will be pulled high or low depending on the
whether MCO is set or cleared.
The I2CTX bit contains the R/W bit sent from the master. If
I2CTX is set, the master would like to receive a byte. Therefore,
the slave will transmit data by writing to the I2CDAT register.
If I2CTX is cleared, the master would like to transmit a byte.
Therefore, the slave will receive a serial byte. The software can
interrogate the state of I2CTX to determine whether it should
write to or read from I2CDAT.
To receive data, MDE must be cleared to disable the output driver
on SDATA. Software must provide the clocks by toggling the
MCO bit and reading the SDATA pin via the MDI bit. If MDE
is cleared, MDI can be used to read the SDATA pin. The value of
the SDATA pin is latched into MDI on a rising edge of SCLOCK.
MDI is set if the SDATA pin was high on the last rising edge of
SCLOCK. MDI is clear if the SDATA pin was low on the last
rising edge of SCLOCK.
Once the ADuC836 has received a valid address, hardware will
hold SCLOCK low until the I2CI bit is cleared by the software.
This allows the master to wait for the slave to be ready before
transmitting the clocks for the next byte.
Software must control MDO, MCO, and MDE appropriately to
generate the START condition, slave address, acknowledge bits,
data bytes, and STOP conditions. These functions are provided
in Application Note uC001.
Hardware Slave Mode
After reset, the ADuC836 defaults to hardware Slave mode. The
I2C interface is enabled by clearing the SPE bit in SPICON.
Slave mode is enabled by clearing the I2CM bit in I2CCON.
The ADuC836 has a full hardware slave. In Slave mode, the I2C
address is stored in the I2CADD register. Data received or to be
transmitted is stored in the I2CDAT register.
REV. A
The I2CI interrupt bit will be set every time a complete data byte
is received or transmitted provided it is followed by a valid ACK.
If the byte is followed by a NACK, an interrupt is generated. The
ADuC836 will continue to issue interrupts for each complete
data byte transferred until a STOP condition is received or the
interface is reset.
When a STOP condition is received, the interface will reset to a
state where it is waiting to be addressed (idle). Similarly, if the
interface receives a NACK at the end of a sequence, it also returns
to the default idle state. The I2CRS bit can be used to reset the
I2C interface. This bit can be used to force the interface back to
the default idle state.
It should be noted that there is no way (in hardware) to distinguish
between an interrupt generated by a received START + valid
address and an interrupt generated by a received data byte. User
software must be used to distinguish between these interrupts.
–47–
ADuC836
DUAL DATA POINTER
DPCON
Data Pointer Control SFR
The ADuC836 incorporates both main and shadow data pointers.
The shadow data pointer is selected via the data pointer control
SFR (DPCON). DPCON also includes features such as automatic
hardware post-increment and post-decrement, as well as automatic
data pointer toggle. DPCON is described in Table XXIII.
SFR Address
Power-On Default Value
Bit Addressable
A7H
00H
No
Table XXIII. DPCON SFR Bit Designations
Bit
Name
Description
7
–––
Reserved for Future Use
6
DPT
Data Pointer Automatic Toggle Enable.
Cleared by user to disable auto swapping of the DPTR.
Set in user software to enable automatic toggling of the DPTR after each MOVX or MOVC instruction.
5
DP1m1
Shadow Data Pointer Mode.
4
DP1m0
These two bits enable extra modes of the shadow data pointer operation, allowing for more compact and more
efficient code size and execution.
m1
m0
Behavior of the Shadow Data Pointer
0
0
8052 Behavior
0
1
DPTR is post-incremented after a MOVX or MOVC instruction.
1
0
DPTR is post-decremented after a MOVX or MOVC instruction.
1
1
DPTR LSB is toggled after a MOVX or MOVC instruction.
(This instruction can be useful for moving 8-bit blocks to/from 16-bit devices.)
3
DP0m1
Main Data Pointer Mode.
2
DP0m0
These two bits enable extra modes of the main data pointer operation, allowing for more compact and more
efficient code size and execution.
m1
m0
Behavior of the Main Data Pointer
0
0
8052 Behavior
0
1
DPTR is post-incremented after a MOVX or MOVC instruction.
1
0
DPTR is post-decremented after a MOVX or MOVC instruction.
1
1
DPTR LSB is toggled aftera MOVX or MOVC instruction.
(This instruction can be useful for moving 8-bit blocks to/from 16-bit devices.)
1
–––
This bit is not implemented to allow the INC DPCON instruction to toggle the data pointer without incrementing the rest of the SFR.
0
DPSEL
Data Pointer Select.
Cleared by user to select the main data pointer. This means that the contents of the main 24-bit DPTR appears
in the three SFRs: DPL, DPH, and DPP.
Set by user to select the shadow data pointer. This means that the contents of the shadow 24-bit DPTR
appears in the three SFRs: DPL, DPH, and DPP.
NOTES
1. This is the only place where the main and shadow data pointers are distinguished. Everywhere else in this data sheet, wherever the DPTR is mentioned, operation on the
active DPTR is implied.
2. Only MOVC/MOVX @DPTR instructions are relevant above. MOVC/MOVX [email protected] instructions will not cause the DPTR to automatically post increment/decrement,
and so on. To illustrate the operation of DPCON, the following code will copy 256 bytes of code memory at address D000H into XRAM starting from address 0000H.
the code uses 16 bytes and 2054 cycles. To perform this on a standard 8051 requires approximately 33 bytes and 7172 cycles (depending on how it is implemented).
MOV
MOV
DPTR,#0
DPCON,#55h
MOV DPTR,#0D000h
MOVELOOP:
CLR A
;
;
;
;
;
;
Main DPTR = 0
Select shadow DPTR
DPTR1 increment mode,
DPTR0 increment mode
DPTR auto toggling ON
Shadow DPTR = D000h
MOVC A,@A+DPTR
MOVX @DPTR,A
MOV
JNZ
–48–
;
;
;
;
;
;
Get data
Post Inc DPTR
Swap to Main DPTR (Data)
Put ACC in XRAM
Increment main DPTR
Swap to Shad DPTR (Code)
A, DPL
MOVELOOP
REV. A
ADuC836
8052 COMPATIBLE ON-CHIP PERIPHERALS
Port 1
This section gives a brief overview of the various secondary
peripheral circuits, which are also available to the user on-chip.
These remaining functions are mostly 8052 compatible (with
a few additional features) and are controlled via standard 8052
SFR bit definitions.
Port 1 is also an 8-bit port directly controlled via the P1 SFR.
The Port 1 pins are divided into two distinct pin groupings: P1.0
to P1.1 and P1.2 to P1.7.
P1.0 and P1.1
P1.0 and P1.1 are bidirectional digital I/O pins with internal
pull-ups.
Parallel I/O
The ADuC836 uses four input/output ports to exchange data
with external devices. In addition to performing general-purpose
I/O, some ports are capable of external memory operations while
others are multiplexed with alternate functions for the peripheral
features on the device. In general, when a peripheral is enabled,
that pin may not be used as a general-purpose I/O pin.
If P1.0 and P1.1 have 1s written to them via the P1 SFR, they are
pulled high by the internal pull-up resistors. In this state, they can
also be used as inputs. As input pins being externally pulled low,
they will source current because of the internal pull-ups. With 0s
written to them, both of these pins will drive a logic low output
voltage (VOL) and will be capable of sinking 10 mA compared to
the standard 1.6 mA sink capability on the other port pins.
Port 0
Port 0 is an 8-bit open-drain bidirectional I/O port that is directly
controlled via the Port 0 SFR. Port 0 is also the multiplexed low
order address and data bus during accesses to external program
or data memory.
Figure 36 shows a typical bit latch and I/O buffer for a Port 0
port pin. The bit latch (one bit in the port’s SFR) is represented
as a Type D flip-flop, which will clock in a value from the internal
bus in response to a “write to latch” signal from the CPU. The Q
output of the flip-flop is placed on the internal bus in response to
a “read latch” signal from the CPU. The level of the port pin itself
is placed on the internal bus in response to a “read pin” signal
from the CPU. Some instructions that read a port activate the
“read latch” signal, and others activate the “read pin” signal. See
the Read-Modify-Write Instructions section for more details.
ADDR/DATA
READ
LATCH
INTERNAL
BUS
WRITE
TO LATCH
DVDD
CONTROL
D
Q
These pins also have various secondary functions described in
Table XXIV. The Timer 2 alternate functions of P1.0 and P1.1
can only be activated if the corresponding bit latch in the P1 SFR
contains a 1. Otherwise, the port pin is stuck at 0. In the case of
the PWM outputs at P1.0 and P1.1, the PWM outputs will overwrite anything written to P1.0 or P1.1.
Table XXIV. P1.0 and P1.1 Alternate Pin Functions
Pin
Alternate Function
P1.0
T2 (Timer/Counter 2 External Input)
PWM0 (PWM0 output at this pin)
T2EX (Timer/Counter 2 Capture/Reload Trigger)
PWM1 (PWM1 output at this pin)
P1.1
Figure 37 shows a typical bit latch and I/O buffer for a P1.0 or
P1.1 port pin. No external memory access is required from either
of these pins, although internal pull-ups are present.
DVDD
P0.x
PIN
READ
LATCH
CL Q
LATCH
INTERNAL
BUS
Figure 36. Port 0 Bit Latch and I/O Buffer
In general-purpose I/O port mode, Port 0 pins that have 1s written to them via the Port 0 SFR will be configured as open-drain
and therefore will float. In this state, Port 0 pins can be used as
high impedance inputs. This is represented in Figure 36 by the
NAND gate whose output remains high as long as the CONTROL
signal is low, thereby disabling the top FET. External pull-up
resistors are therefore required when Port 0 pins are used as
general-purpose outputs. Port 0 pins with 0s written to them will
drive a logic low output voltage (VOL) and will be capable of sinking 1.6 mA.
REV. A
D
WRITE
TO LATCH
READ
PIN
As shown in Figure 36, the output drivers of Port 0 pins are
switchable to an internal ADDR and ADDR/DATA bus by an
internal CONTROL signal for use in external memory accesses.
During external memory accesses, the P0 SFR is written with
1s (i.e., all of its bit latches become 1s). When accessing external
memory, the CONTROL signal in Figure 36 goes high, enabling
push-pull operation of the output pin from the internal address
or data bus (ADDR/DATA line). Therefore, no external pull-ups
are required on Port 0 for it to access external memory.
ALTERNATE
OUTPUT FUNCTION
INTERNAL
PULL-UP*
P1.x
PIN
Q
CL Q
LATCH
READ
PIN
ALTERNATE
INPUT
FUNCTION
*SEE FIGURE 38
FOR DETAILS OF
INTERNAL PULL-UP
Figure 37. P1.0 and P1.1 Bit Latch and I/O Buffer
The internal pull-up consists of active circuitry, as shown in
Figure 38. Whenever a P1.0 or P1.1 bit latch transitions from low
to high, Q1 in Figure 38 turns on for two oscillator periods to
quickly pull the pin to a logic high state. Once there, the weaker
Q3 turns on, thereby latching the pin to a logic high. If the pin
is momentarily pulled low externally, Q3 will turn off, but the
very weak Q2 will continue to source some current into the pin,
attempting to restore it to a logic high.
DVDD
2 CLK
DELAY
Q
FROM
PORT
LATCH
Q1
DVDD
Q2
DVDD
Q3
Q4
Figure 38. Internal Pull-Up Configuration
–49–
Px.x
PIN
ADuC836
P1.2 to P1.7
Port 3 pins also have various secondary functions described in
Table XXV. The alternate functions of Port 3 pins can be activated
only if the corresponding bit latch in the P3 SFR contains a 1.
Otherwise, the port pin is stuck at 0.
The remaining Port 1 pins (P1.2 to P1.7) can only be configured as
analog input (ADC) or digital input pins. By (power-on) default,
these pins are configured as analog inputs, i.e., 1 written in the
corresponding Port 1 register bit. To configure any of these pins
as digital inputs, the user should write a 0 to these port bits to
configure the corresponding pin as a high impedance digital input.
Figure 39 illustrates this function. Note that there are no output
drivers for Port 1 pins, and they therefore cannot be used as
outputs.
Table XXV. Port 3, Alternate Pin Functions
WRITE
TO LATCH
D
Q
CL
Q
LATCH
READ
PIN
TO ADC
Alternate Function
P3.0
RxD (UART Input Pin)
(or Serial Data I/O in Mode 0)
TxD (UART Output Pin)
(or Serial Clock Output in Mode 0)
INT0 (External Interrupt 0)
INT1 (External Interrupt 1)
T0 (Timer/Counter 0 External Input)
PWMCLK (PWM External Clock)
T1 (Timer/Counter 1 External Input)
WR (External Data Memory Write Strobe)
RD (External Data Memory Read Strobe)
P3.1
READ
LATCH
INTERNAL
BUS
Pin
P3.2
P3.3
P3.4
P1.x
PIN
P3.5
P3.6
P3.7
Figure 39. P1.2 to P1.7 Bit Latch and I/O Buffer
Port 2
Port 3 pins have the same bit latch and I/O buffer configurations
as the P1.0 and P1.1, as shown in Figure 41. The internal pull-up
configuration is also defined by the one in Figure 38.
Port 2 is a bidirectional port with internal pull-up resistors directly
controlled via the P2 SFR. Port 2 also emits the high order address
bytes during fetches from external program memory and middle
and high order address bytes during accesses to the 24-bit external
data memory space.
DVDD
READ
LATCH
As shown in Figure 40, the output drivers of Port 2 are switchable
to an internal ADDR bus by an internal CONTROL signal for use
in external memory accesses (as for Port 0). In external memory
addressing mode (CONTROL = 1), the port pins feature push/
pull operation controlled by the internal address bus (ADDR line).
However, unlike the P0 SFR during external memory accesses,
the P2 SFR remains unchanged.
INTERNAL
BUS
WRITE
TO LATCH
In general-purpose I/O port mode, Port 2 pins that have 1s written
to them are pulled high by the internal pull-ups (Figure 38), and in
that state can be used as inputs. As inputs, Port 2 pins being pulled
externally low will source current because of the internal pull-up
resistors. Port 2 pins with 0s written to them will drive a logic low
output voltage (VOL) and will be capable of sinking 1.6 mA.
ADDR
CONTROL
READ
LATCH
INTERNAL
PULL-UP*
INTERNAL
BUS
D
Q
WRITE
TO LATCH
CL
Q
READ
PIN
DVDD DVDD
P2.x
PIN
LATCH
*SEE FIGURE 38 FOR
DETAILS OF INTERNAL PULL-UP
ALTERNATE
OUTPUT
FUNCTION
D
Q
CL
Q
INTERNAL
PULL-UP*
P3.x
PIN
LATCH
READ
PIN
ALTERNATE
INPUT
FUNCTION
*SEE FIGURE 38
FOR DETAILS OF
INTERNAL PULL-UP
Figure 41. Port 3 Bit Latch and I/O Buffer
Additional Digital I/O
In addition to the port pins, the dedicated SPI/I2C pins (SCLOCK
and SDATA/MOSI) also feature both input and output functions.
Their equivalent I/O architectures are illustrated in Figure 42 and
Figure 44, respectively, for SPI operation, and in Figure 43 and
Figure 45 for I2C operation.
Notice that in I2C mode (SPE = 0), the strong pull-up FET (Q1) is
disabled leaving only a weak pull-up (Q2) present. By contrast, in
SPI mode (SPE = 1), the strong pull-up FET (Q1) is controlled
directly by SPI hardware, giving the pin push/pull capability.
Port 3 is a bidirectional port with internal pull-ups directly controlled
via the P3 SFR.
In I2C mode (SPE = 0), two pull-down FETs (Q3 and Q4)
operate in parallel in order to provide an extra 60% or 70% of
current sinking capability. In SPI mode, however, (SPE = 1), only
one of the pull-down FETs (Q3) operates on each pin resulting
in sink capabilities identical to that of Port 0 and Port 2 pins.
Port 3 pins that have 1s written to them are pulled high by the
internal pull-ups, and in that state can be used as inputs. As inputs,
Port 3 pins being pulled externally low will source current because
of the internal pull-ups. Port 3 pins with 0s written to them will
drive a logic low output voltage (VOL) and will be capable of sinking 1.6 mA.
On the input path of SCLOCK, notice that a Schmitt trigger
conditions the signal going to the SPI hardware to prevent false
triggers (double triggers) on slow incoming edges. For incoming
signals from the SCLOCK and SDATA pins going to I2C hardware,
a filter conditions the signals to reject glitches of up to 50 ns in
duration.
Figure 40. Port 2 Bit Latch and I/O Buffer
Port 3
–50–
REV. A
ADuC836
Notice also that direct access to the SCLOCK and SDATA/MOSI
pins is afforded through the SFR interface in I2C master mode.
Therefore, if you are not using the SPI or I2C functions, you can
use these two pins to provide additional high current digital outputs.
DVDD
SPE = 1 (SPI ENABLE)
Q1
As shown in Figure 46, the MISO pin in SPI master/slave operation offers the exact same pull-up and pull-down configuration as
the MOSI pin in SPI slave/master operation.
The SS pin has a weak internal pull-up permanently enabled to
prevent the SS input from floating. This pull-up can be easily
overdriven by an external device to drive the SS pin low.
DVDD
Q2 (OFF)
HARDWARE SPI
(MASTER/SLAVE)
SCLOCK
PIN
SCHMITT
TRIGGER
Q4 (OFF)
HARDWARE SPI
(MASTER/SLAVE)
Q3
Figure 42. SCLOCK Pin I/O Functional Equivalent
in SPI Mode
DVDD
HARDWARE I2C
(SLAVE ONLY)
SFR
BITS
Figure 46. MISO Pin I/O Functional Equivalent
DVDD
SPE = 0 (I2C ENABLE)
Q1
(OFF)
Q2
50ns GLITCH
REJECTION FILTER
HARDWARE SPI
(MASTER/SLAVE)
SCLOCK
PIN
MCO
I2CM
Read-Modify-Write Instructions
Figure 43. SCLOCK Pin I/O Functional Equivalent
in I2C Mode
DVDD
SPE = 1 (SPI ENABLE)
Q1
Q2 (OFF)
SDATA/
MOSI
PIN
HARDWARE SPI
(MASTER/SLAVE)
Q4 (OFF)
Q3
Figure 44. SDATA/MOSI Pin I/O Functional Equivalent
in SPI Mode
DVDD
SPE = 0 (I2C ENABLE)
SFR
BITS
Q1
(OFF)
Q2
SDATA/
MOSI
PIN
Q4
MDO
Some 8051 instructions that read a port, read the latch and
others read the pin. The instructions that read the latch rather
than the pins are the ones that read a value, possibly change it,
and then rewrite it to the latch. These are called “read-modifywrite” instructions. which are listed below. When the destination
operand is a port or a port bit, these instructions read the latch
rather than the pin.
ANL
ORL
XRL
JBC
(Logical AND, e.g., ANL P1, A)
(Logical OR, e.g., ORL P2, A)
(Logical EX-OR, e.g., XRL P3, A)
(Jump If Bit = 1 and Clear Bit,
e.g., JBC P1.1, LABEL
CPL
(Complement Bit, e.g., CPL P3.0)
INC
(Increment, e.g., INC P2)
DEC
(Decrement, e.g., DEC P2)
DJNZ
(Decrement and Jump IFf Not Zero,
e.g.,DJNZ P3, LABEL)
MOV PX.Y, C* (Move Carry to Bit Y of Port X)
CLR PX.Y*
(Clear Bit Y of Port X)
SETB PX.Y*
(Set Bit Y of Port X)
*These instructions read the port byte (all eight bytes), modify the addressed bit
and then write the new byte back to the latch.
50ns GLITCH
REJECTION FILTER
MDI
MDE
Q3
I2CM
The reason that read-modify-write instructions are directed to
the latch rather than to the pin is to avoid a possible misinterpretation of the voltage level of a pin. For example, a port pin
might be used to drive the base of a transistor. When a 1 is written
to the bit, the transistor is turned on. If the CPU then reads the
same port bit at the pin rather than the latch, it will read the base
voltage of the transistor and interpret it as a Logic 0. Reading the
latch rather than the pin will return the correct value of 1.
Figure 45. SDATA/MOSI Pin I/O Functional Equivalent
in I2C Mode
REV. A
SS
PIN
Figure 47. SS Pin I/O Functional Equivalent
Q4
Q3
HARDWARE I2C
(SLAVE ONLY)
MISO
PIN
–51–
ADuC836
TIMERS/COUNTERS
The ADuC836 has three 16-bit Timer/Counters: Timer 0, Timer 1,
and Timer 2. The Timer/Counter hardware has been included
on-chip to relieve the processor core of the overhead inherent in
implementing timer/counter functionality in software. Each
Timer/Counter consists of two 8-bit registers: THx and TLx
(x = 0, 1, and 2). All three can be configured to operate either as
timers or event counters.
In Timer function, the TLx Register is incremented every machine
cycle. Thus it can be viewed as counting machine cycles. Since
a machine cycle consists of 12 core clock periods, the maximum
count rate is 1/12 of the core clock frequency.
every machine cycle. When the samples show a high in one cycle
and a low in the next cycle, the count is incremented. The new
count value appears in the register during S3P1 of the cycle following the one in which the transition was detected. Since it takes
two machine cycles (16 core clock periods) to recognize a 1-to-0
transition, the maximum count rate is 1/16 of the core clock frequency. There are no restrictions on the duty cycle of the external
input signal, but to ensure that a given level is sampled at least
once before it changes, it must be held for a minimum of one full
machine cycle. Remember that the core clock frequency is programmed via the CD0–2 selection bits in the PLLCON SFR.
User configuration and control of the timers is achieved via three
main SFRs: TMOD and TCON control the configuration of
Timers 0 and 1, while T2CON configures Timer 2.
In Counter function, the TLx Register is incremented by a 1-to-0
transition at its corresponding external input pin, T0, T1, or T2.
In this function, the external input is sampled during S5P2 of
TMOD
Timer/Counter 0 and 1 Mode Register
SFR Address
Power-On Default Value
Bit Addressable
89H
00H
No
Table XXVI. TMOD SFR Bit Designations
Bit
Name
Description
7
Gate
Timer 1 Gating Control.
Set by software to enable Timer/Counter 1 only while INT1 pin is high and TR1 control bit is set.
Cleared by software to enable Timer 1 whenever TR1 control bit is set.
6
C/T
Timer 1 Timer or Counter Select Bit.
Set by software to select counter operation (input from T1 pin).
Cleared by software to select timer operation (input from internal system clock).
5
M1
Timer 1 Mode Select Bit 1 (used with M0 Bit)
4
M0
Timer 1 Mode Select Bit 0.
M1
M0
0
0
TH1 operates as an 8-bit timer/counter. TL1 serves as 5-bit prescaler.
0
1
16-Bit Timer/Counter. TH1 and TL1 are cascaded; there is no prescaler.
1
0
8-Bit Autoreload Timer/Counter. TH1 holds a value that is to be reloaded into TL1 each
time it overflows.
1
1
Timer/Counter 1 stopped.
3
Gate
Timer 0 Gating Control.
Set by software to enable Timer/Counter 0 only while INT0 pin is high and TR0 control bit is set.
Cleared by software to enable Timer 0 whenever TR0 control bit is set.
2
C/T
Timer 0 Timer or Counter Select Bit.
Set by software to select counter operation (input from T0 pin).
Cleared by software to select timer operation (input from internal system clock).
1
M1
Timer 0 Mode Select Bit 1
0
M0
Timer 0 Mode Select Bit 0.
M1
M0
0
0
TH0 operates as an 8-bit timer/counter. TL0 serves as 5-bit prescaler.
0
1
16-Bit Timer/Counter. TH0 and TL0 are cascaded; there is no prescaler.
1
0
8-Bit Autoreload Timer/Counter. TH0 holds a value that is to be reloaded into TL0 each time
it overflows.
1
1
TL0 is an 8-bit timer/counter controlled by the standard Timer 0 control bits. TH0 is an 8-bit
timer only, controlled by Timer 1 control bits.
–52–
REV. A
ADuC836
TCON
Timer/Counter 0 and 1 Control Register
SFR Address
Power-On Default Value
Bit Addressable
88H
00H
Yes
Table XXVII. TCON SFR Bit Designations
Bit
Name
Description
7
TF1
Timer 1 Overflow Flag.
Set by hardware on a Timer/Counter 1 overflow.
Cleared by hardware when the Program Counter (PC) vectors to the interrupt service routine.
6
TR1
Timer 1 Run Control Bit.
Set by user to turn on Timer/Counter 1.
Cleared by user to turn off Timer/Counter 1.
5
TF0
Timer 0 Overflow Flag.
Set by hardware on a Timer/Counter 0 overflow.
Cleared by hardware when the PC vectors to the interrupt service routine.
4
TR0
Timer 0 Run Control Bit.
Set by user to turn on Timer/Counter 0.
Cleared by user to turn off Timer/Counter 0.
3
IE1*
External Interrupt 1 (INT1) Flag.
Set by hardware by a falling edge or zero level being applied to external interrupt pin INT1, depending on bit IT1 state.
Cleared by hardware when the PC vectors to the interrupt service routine only if the interrupt was transitionactivated. If level-activated, the external requesting source rather than the on-chip hardware, controls the request flag.
2
IT1*
External Interrupt 1 (IE1) Trigger Type.
Set by software to specify edge-sensitive detection (i.e., 1-to-0 transition).
Cleared by software to specify level-sensitive detection (i.e., zero level).
1
IE0*
External Interrupt 0 (INT0) Flag.
Set by hardware by a falling edge or zero level being applied to external interrupt pin INT0, depending on bit IT0 state.
Cleared by hardware when the PC vectors to the interrupt service routine only if the interrupt was transitionactivated. If level-activated, the external requesting source controls the request flag, rather than the on-chip hardware.
0
IT0*
External Interrupt 0 (IE0) Trigger Type.
Set by software to specify edge-sensitive detection (i.e., 1-to-0 transition).
Cleared by software to specify level-sensitive detection (i.e., zero level).
*These bits are not used in the control of Timer/Counter 0 and 1, but are used instead in the control and monitoring of the external INT0 and INT1 interrupt pins.
Timer/Counter 0 and 1 Data Registers
Both Timer 0 and Timer 1 consist of two 8-bit registers. These can be used as independent registers or combined to be a single 16-bit
register, depending on the timer mode configuration.
TH0 and TL0
Timer 0 high byte and low byte.
SFR Address = 8CH, 8AH, respectively.
TH1 and TL1
Timer 1 high byte and low byte.
SFR Address = 8DH, 8BH, respectively.
REV. A
–53–
ADuC836
TIMER/COUNTER 0 AND 1 OPERATING MODES
Mode 2 (8-Bit Timer/Counter with Auto Reload)
The following paragraphs describe the operating modes for Timer/
Counters 0 and 1. Unless otherwise noted, it should be assumed
that these modes of operation are the same for both Timer 0 and 1.
Mode 2 configures the timer register as an 8-bit counter (TL0)
with automatic reload, as shown in Figure 50. Overflow from TL0
not only sets TF0, but also reloads TL0 with the contents of TH0,
which are preset by software. The reload leaves TH0 unchanged.
Mode 0 (13-Bit Timer/Counter)
Mode 0 configures an 8-bit timer/counter with a divide-by-32
prescaler. Figure 48 shows Mode 0 operation.
CORE
CLK*
 12
C/ T = 0
CORE
CLK*
TL0
(8 BITS)
 12
C/ T = 0
TL0
TH0
(5 BITS) (8 BITS)
C/ T = 1
TF0
INTERRUPT
TF0
C/ T = 1
INTERRUPT
P3.4/T0
CONTROL
TR0
P3.4/T0
CONTROL
TR0
RELOAD
TH0
(8 BITS)
GATE
P3.2/INT0
*THE CORE CLOCK IS THE OUTPUT OF THE PLL (SEE THE ON-CHIP PLL SECTION)
GATE
P3.2/INT0
Figure 50. Timer/Counter 0, Mode 2
*THE CORE CLOCK IS THE OUTPUT OF THE PLL (SEE THE ON-CHIP PLL SECTION)
Mode 3 (Two 8-Bit Timer/Counters)
Figure 48. Timer/Counter 0, Mode 0
In this mode, the timer register is configured as a 13-bit register.
As the count rolls over from all 1s to all 0s, it sets the timer overflow flag. The overflow flag, TF0, can then be used to request an
interrupt. The counted input is enabled to the timer when TR0 = 1
and either Gate = 0 or INT0 = 1. Setting Gate = 1 allows the
timer to be controlled by external input INT0 to facilitate pulsewidth measurements. TR0 is a control bit in the special function
register TCON; Gate is in TMOD. The 13-bit register consists
of all eight bits of TH0 and the lower five bits of TL0. The upper
three bits of TL0 are indeterminate and should be ignored. Setting
the run flag (TR0) does not clear the registers.
Mode 1 (16-Bit Timer/Counter)
Mode 3 has different effects on Timer 0 and Timer 1. Timer 1 in
Mode 3 simply holds its count. The effect is the same as setting
TR1 = 0. Timer 0 in Mode 3 establishes TL0 and TH0 as two
separate counters. This configuration is shown in Figure 51. TL0
uses the Timer 0 control bits: C/T, Gate, TR0, INT0, and TF0.
TH0 is locked into a timer function (counting machine cycles)
and takes over the use of TR1 and TF1 from Timer 1. Thus, TH0
now controls the Timer 1 interrupt. Mode 3 is provided for applications requiring an extra 8-bit timer or counter.
When Timer 0 is in Mode 3, Timer 1 can be turned on and off by
switching it out of and into its own Mode 3, or it can still be used by
the serial interface as a baud rate generator. In fact, it can be used in
any application not requiring an interrupt from Timer 1 itself.
Mode 1 is the same as Mode 0, except that the timer register is
running with all 16 bits. Mode 1 is shown in Figure 49.
CORE
CLK*
CORE
CLK/12
 12
C/ T = 0
CORE
CLK*
 12
C/ T = 0
TL0
TH0
(8 BITS) (8 BITS)
INTERRUPT
TL0
(8 BITS)
TF0
TH0
(8 BITS)
TF1
C/ T = 1
INTERRUPT
P3.4/T0
TF0
CONTROL
TR0
C/ T = 1
P3.4/T0
TR0
CONTROL
GATE
P3.2/INT0
GATE
CORE
CLK/12
P3.2/INT0
INTERRUPT
TR1
*THE CORE CLOCK IS THE OUTPUT OF THE PLL (SEE THE ON-CHIP PLL SECTION)
*THE CORE CLOCK IS THE OUTPUT OF THE PLL (SEE THE ON-CHIP PLL SECTION)
Figure 49. Timer/Counter 0, Mode 1
Figure 51. Timer/Counter 0, Mode 3
–54–
REV. A
ADuC836
TIMER/COUNTER 2 OPERATING MODES
16-Bit Capture Mode
The following paragraphs describe the operating modes for
Timer/Counter 2. The operating modes are selected by bits in the
T2CON SFR, as shown in Table XXIX.
Capture Mode has two options, which are selected by bit EXEN2
in T2CON. If EXEN2 = 0, Timer 2 is a 16-bit timer or counter
that, upon overflowing, sets bit TF2, the Timer 2 overflow bit,
which can be used to generate an interrupt. If EXEN2 = 1, Timer 2
still performs the above, but a l-to-0 transition on external input
T2EX causes the current value in the Timer 2 registers, TL2
and TH2, to be captured into registers RCAP2L and RCAP2H,
respectively. In addition, the transition at T2EX causes bit EXF2
in T2CON to be set; EXF2, like TF2, can generate an interrupt.
Capture mode is illustrated in Figure 53.
Table XXVIII. Timer 2 Operating Modes
RCLK (or) TCLK
CAP2
TR2
MODE
0
0
1
X
0
1
X
X
1
1
1
0
16-Bit Autoreload
16-Bit Capture
Baud Rate
OFF
The baud rate generator mode is selected by RCLK = 1 and/or
TCLK = 1.
16-Bit Autoreload Mode
Autoreload mode has two options, which are selected by bit
EXEN2 in T2CON. If EXEN2 = 0, when Timer 2 rolls over,
it not only sets TF2 but also causes the Timer 2 registers to be
reloaded with the 16-bit value in registers RCAP2L and RCAP2H,
which are preset by software. If EXEN2 = 1, Timer 2 still
performs the above, but with the added feature that a 1-to-0 transition at external input T2EX will also trigger the 16-bit reload
and set EXF2. The Autoreload mode is illustrated in Figure 52.
CORE
CLK*
12
In either case, if Timer 2 is being used to generate the baud rate,
the TF2 interrupt flag will not occur. Therefore Timer 2 interrupts will not occur so they do not have to be disabled. However,
in this mode, the EXF2 flag can still cause interrupts and this can
be used as a third external interrupt.
Baud rate generation will be described as part of the UART serial
port operation.
C/ T2 = 0
C/ T2 = 1
T2
PIN
TL2
(8 BITS)
TH2
(8 BITS)
RCAP2L
RCAP2H
CONTROL
TR2
RELOAD
TRANSITION
DETECTOR
TF2
TIMER
INTERRUPT
T2EX
PIN
EXF2
CONTROL
EXEN2
*THE CORE CLOCK IS THE OUTPUT OF THE PLL (SEE THE ON-CHIP PLL SECTION)
Figure 52. Timer/Counter 2, 16-Bit Autoreload Mode
CORE
CLK*
12
C/ T2 = 0
TL2
(8 BITS)
C/ T2 = 1
T2
PIN
TH2
(8 BITS)
TF2
CONTROL
TR2
TIMER
INTERRUPT
CAPTURE
TRANSITION
DETECTOR
RCAP2L
T2EX
PIN
RCAP2H
EXF2
CONTROL
EXEN2
*THE CORE CLOCK IS THE OUTPUT OF THE PLL (SEE THE ON-CHIP PLL SECTION)
Figure 53. Timer/Counter 2, 16-Bit Capture Mode
REV. A
–55–
ADuC836
T2CON
Timer/Counter 2 Control Register
SFR Address
Power-On Default Value
Bit Addressable
C8H
00H
Yes
Table XXIX. T2CON SFR Bit Designations
Bit
Name
Description
7
TF2
Timer 2 Overflow Flag.
Set by hardware on a Timer 2 overflow. TF2 will not be set when either RCLK or TCLK = 1.
Cleared by user software.
6
EXF2
Timer 2 External Flag.
Set by hardware when either a capture or a reload is caused by a negative transition in T2EX and EXEN2 = 1.
Cleared by user software.
5
RCLK
Receive Clock Enable Bit.
Set by user to enable the serial port to use Timer 2 overflow pulses for its receive clock in serial port Modes 1 and 3.
Cleared by user to enable Timer 1 overflow to be used for the receive clock.
4
TCLK
Transmit Clock Enable Bit.
Set by user to enable the serial port to use Timer 2 overflow pulses for its transmit clock in serial port Modes 1 and 3.
Cleared by user to enable Timer 1 overflow to be used for the transmit clock.
3
EXEN2
Timer 2 External Enable Flag.
Set by user to enable a capture or reload to occur as a result of a negative transition on T2EX if Timer 2 is not
being used to clock the serial port.
Cleared by user for Timer 2 to ignore events at T2EX.
2
TR2
Timer 2 Start/Stop Control Bit.
Set by user to start Timer 2.
Cleared by user to stop Timer 2.
1
CNT2
Timer 2 Timer or Counter Function Select Bit.
Set by user to select counter function (input from external T2 pin).
Cleared by user to select timer function (input from on-chip core clock).
0
CAP2
Timer 2 Capture/Reload Select Bit.
Set by user to enable captures on negative transitions in T2EX when EXEN2 = 1.
Cleared by user to enable auto reloads with Timer 2 overflows or negative transitions in T2EX when EXEN2 = 1.
When either RCLK = 1 or TCLK = 1, this bit is ignored and the timer is forced to autoreload on Timer 2 overflow.
Timer/Counter 2 Data Registers
Timer/Counter 2 also has two pairs of 8-bit data registers associated with it. These are used as both timer data registers and timer
capture/reload registers.
TH2 and TL2
Timer 2, data high byte and low byte.
SFR Address = CDH, CCH, respectively.
RCAP2H and RCAP2L
Timer 2, Capture/Reload byte and low byte.
SFR Address = CBH, CAH, respectively.
–56–
REV. A
ADuC836
SBUF
UART SERIAL INTERFACE
The serial port is full-duplex, meaning it can transmit and receive
simultaneously. It is also receive-buffered, meaning it can commence reception of a second byte before a previously received byte
has been read from the receive register. However, if the first byte
still has not been read by the time reception of the second byte is
complete, the first byte will be lost. The physical interface to the
serial data network is via pins RxD(P3.0) and TxD(P3.1), while
the SFR interface to the UART comprises the following registers:
SCON
UART Serial Port Control Registers
SFR Address
Power-On Default Value
Bit Addressable
98H
00H
Yes
The serial port receive and transmit registers are both accessed
through the SBUF SFR (SFR address = 99H). Writing to SBUF
loads the transmit register, and reading SBUF accesses a physically separate receive register.
Table XXX. SCON SFR Bit Designations
Bit
Name
Description
7
SM0
UART Serial Mode Select Bits.
6
SM1
These bits select the Serial Port operating mode as follows:
SM0
SM1
Selected Operating Mode
0
0
Mode 0: Shift Register, fixed baud rate (fCORE/12)
0
1
Mode 1: 8-bit UART, variable baud rate
1
0
Mode 2: 9-bit UART, fixed baud rate (fCORE/64) or (fCORE/32)
1
1
Mode 3: 9-bit UART, variable baud rate
5
SM2
Multiprocessor Communication Enable Bit.
Enables multiprocessor communication in Modes 2 and 3. In Mode 0, SM2 should be cleared. In Mode 1, if
SM2 is set, RI will not be activated if a valid stop bit was not received. If SM2 is cleared, RI will be set as soon
as the byte of data has been received. In Modes 2 or 3, if SM2 is set, RI will not be activated if the received ninth
data bit in RB8 is 0. If SM2 is cleared, RI will be set as soon as the byte of data has been received.
4
REN
Serial Port Receive Enable Bit.
Set by user software to enable serial port reception.
Cleared by user software to disable serial port reception.
3
TB8
Serial Port Transmit (Bit 9).
The data loaded into TB8 will be the ninth data bit that will be transmitted in Modes 2 and 3.
2
RB8
Serial Port Receiver Bit 9.
The ninth data bit received in Modes 2 and 3 is latched into RB8. For Mode 1, the stop bit is latched into RB8.
1
TI
Serial Port Transmit Interrupt Flag.
Set by hardware at the end of the eighth bit in Mode 0, or at the beginning of the stop bit in Modes 1, 2, and 3.
TI must be cleared by user software.
0
RI
Serial Port Receive Interrupt Flag.
Set by hardware at the end of the eighth bit in Mode 0, or halfway through the stop bit in Modes 1, 2, and 3.
RI must be cleared by software.
UART OPERATING MODES
Mode 0: 8-Bit Shift Register Mode
Mode 0 is selected by clearing both the SM0 and SM1 bits in
the SFR SCON. Serial data enters and exits through RxD. TxD
outputs the shift clock. Eight data bits are transmitted or received.
Transmission is initiated by any instruction that writes to SBUF.
The data is shifted out of the RxD line. The 8 bits are transmitted
with the least significant bit (LSB) first, as shown in Figure 54.
Reception is initiated when the Receive Enable bit (REN) is 1 and
the Receive Interrupt bit (RI) is 0. When RI is cleared, the data
is clocked into the RxD line and the clock pulses are output from
the TxD line.
REV. A
MACHINE
CYCLE 1
MACHINE
CYCLE 2
S1 S2 S3 S4 S5 S6 S1 S2 S3 S4
MACHINE
CYCLE 7
MACHINE
CYCLE 8
S4 S5 S6 S1 S2 S3 S4 S5 S6
CORE
CLK
ALE
RxD
(DATA OUT)
DATA BIT 0
DATA BIT 1
DATA BIT 6
DATA BIT 7
TxD
(SHIFT CLOCK)
Figure 54. UART Serial Port Transmission, Mode 0
–57–
ADuC836
Mode 1: 8-Bit UART, Variable Baud Rate
To transmit, the eight data bits must be written into SBUF. The
ninth bit must be written to TB8 in SCON. When transmission
is initiated, the eight data bits (from SBUF) are loaded onto the
transmit shift register (LSB first). The contents of TB8 are loaded
into the ninth bit position of the transmit shift register.
Mode 1 is selected by clearing SM0 and setting SM1. Each data
byte (LSB first) is preceded by a start bit (0) and followed by a
stop bit (1). Therefore 10 bits are transmitted on TxD or received
on RxD. The baud rate can be set by Timer 1 or Timer 2 (or both).
Alternatively, a dedicated baud rate generator, Timer 3, is provided on-chip to generate high speed, very accurate baud rates.
The transmission will start at the next valid baud rate clock. The
TI flag is set as soon as the stop bit appears on TxD.
Transmission is initiated by writing to SBUF. The “write to
SBUF” signal also loads a 1 (stop bit) into the ninth bit position
of the Transmit Shift Register. The data is output bit by bit until
the stop bit appears on TxD and the transmit interrupt flag (TI)
is automatically set, as shown in Figure 55.
Reception for Mode 2 is similar to that of Mode 1. The eight data
bytes are input at RxD (LSB first) and loaded onto the Receive
Shift Register. When all eight bits have been clocked in, the following events occur:

TxD
START
BIT D0
STOP BIT
D1
D2
D3
D4
D5
D6
D7
TI
(SCON.1)
The eight bits in the Receive Shift Register are latched into
SBUF.

The ninth data bit is latched into RB8 in SCON.

The Receiver Interrupt flag (RI) is set.
If, and only if, the following conditions are met at the time the
final shift pulse is generated:
SET INTERRUPT
i.e., READY FOR MORE
DATA
Figure 55. UART Serial Port Transmission, Mode 0

RI = 0, and
Reception is initiated when a 1-to-0 transition is detected on
RxD. Assuming a valid start bit was detected, character reception
continues. The start bit is skipped and the eight data bits are
clocked into the serial port shift register. When all eight bits have
been clocked in, the following events occur:

Either SM2 = 0, or SM2 = 1 and the received stop bit = 1.

If either of these conditions is not met, the received frame is
irretrievably lost and RI is not set.
Mode 3: 9-Bit UART with Variable Baud Rate
Mode 3 is selected by setting both SM0 and SM1. In this mode,
the 8051 UART serial port operates in 9-bit mode with a variable
baud rate determined by either Timer 1 or Timer 2. The operation
of the 9-bit UART is the same as for Mode 2, but the baud rate
can be varied as for Mode 1.
The eight bits in the Receive Shift Register are latched into
SBUF.

The ninth bit (stop bit) is clocked into RB8 in SCON.

The Receiver Interrupt flag (RI) is set.
In all four modes, transmission is initiated by any instruction
that uses SBUF as a destination register. Reception is initiated in
Mode 0 by the condition RI = 0 and REN = 1. Reception is initiated in the other modes by the incoming start bit if REN = 1.
If, and only if, the following conditions are met at the time, the
final shift pulse is generated:

RI = 0, and

Either SM2 = 0, or SM2 = 1 and the Received Stop Bit = 1.
UART Serial Port Baud Rate Generation
Mode 0 Baud Rate Generation
If either of these conditions is not met, the received frame is
irretrievably lost and RI is not set.
The baud rate in Mode 0 is fixed:
Mode 0 Baud Rate =
Mode 2: 9-Bit UART with Fixed Baud Rate
Mode 2 is selected by setting SM0 and clearing SM1. In this mode,
the UART operates in 9-bit mode with a fixed baud rate. The baud
rate is fixed at Core_Clk/64 by default, although by setting the
SMOD bit in PCON, the frequency can be doubled to Core_Clk/32.
Eleven bits are transmitted or received, a start bit (0), eight data
bits, a programmable ninth bit, and a stop bit (1). The ninth bit
is most often used as a parity bit, although it can be used for anything, including a ninth data bit if required.
fCORE *
12
Mode 2 Baud Rate Generation
The baud rate in Mode 2 depends on the value of the SMOD bit
in the PCON SFR. If SMOD = 0, the baud rate is 1/64 of the
core clock. If SMOD = 1, the baud rate is 1/32 of the core clock:
Mode 2 Baud Rate =
fCORE * × 2SMOD
64
Mode 1 and 3 Baud Rate Generation
Traditionally, the baud rates in Modes 1 and 3 are determined by
the overflow rate in Timer 1 or Timer 2, or both (one for transmit
and the other for receive). On the ADuC836, however, the baud
rate can also be generated via a separate baud rate generator to
achieve higher baud rates and allow all three to be used for other
functions.
*fCORE refers to the output of the PLL as described in the On-Chip PLL section.
–58–
REV. A
ADuC836
BAUD RATE GENERATION USING TIMER 1 AND TIMER 2
Timer 1 Generated Baud Rates
Timer 2 Generated Baud Rates
Baud rates can also be generated using Timer 2. Using Timer 2 is
similar to using Timer 1 in that the timer must overflow 16 times
before a bit is transmitted/received. Because Timer 2 has a 16-bit
Autoreload mode, a wider range of baud rates is possible.
When Timer 1 is used as the baud rate generator, the baud rates
in Modes 1 and 3 are determined by the Timer 1 overflow rate
and the value of SMOD as follows:
(
)
Modes 1 and 3 Baud Rate = 2SMOD ⁄ 32 × (Timer 1 Overflow Rate)
Mode 1 and Mode 3 Baud Rate = (1 16) × (Timer 2 Overflow Rate)
The Timer 1 interrupt should be disabled in this application.
The timer itself can be configured for either timer or counter
operation, and in any of its three running modes. In the most
typical application, it is configured for timer operation, in the
Autoreload mode (high nibble of TMOD = 0100 binary). In this
case, the baud rate is given by the formula:
Therefore when Timer 2 is used to generate baud rates, the timer
increments every two clock cycles and not every core machine
cycle as before. Thus, it increments six times faster than Timer 1,
and therefore baud rates six times faster are possible. Because
Timer 2 has a 16-bit autoreload capability, very low baud rates
are still possible.
Mode 1 and Mode 3 Baud Rate =
Timer 2 is selected as the baud rate generator by setting the TCLK
and/or RCLK in T2CON. The baud rates for transmit and receive
can be simultaneously different. Setting RCLK and/or TCLK puts
Timer 2 into its baud rate generator mode, as shown in Figure 56.
In this case, the baud rate is given by the formula:
fCORE
Mode 1 and Mode 3 Baud Rate =
32 × (65536 − RCAP2H L)
2SMOD × fCORE
32 × 12 (256 − TH1)
A very low baud rate can also be achieved with Timer 1 by leaving
the Timer 1 interrupt enabled, configuring the timer to run as a
16-bit timer (high nibble of TMOD = 0100 binary), and using
the Timer 1 interrupt to do a 16-bit software reload. Table XXXI
shows some commonly used baud rates and how they might
be calculated from a core clock frequency of 1.5728 MHz and
12.58 MHz using Timer 1. Generally speaking, a 5% error is
tolerable using asynchronous (start/stop) communications.
Table XXXII shows some commonly used baud rates and
how they might be calculated from a core clock frequency of
1.5728 MHz and 12.5829 MHz using Timer 2.
Table XXXI. Commonly Used Baud Rates, Timer 1
Table XXXII. Commonly Used Baud Rates, Timer 2
Ideal
Baud
Core
CLK
SMOD
Value
TH1-Reload
Value
Actual
Baud
%
Error
Ideal
Baud
Core
CLK
RCAP2H
Value
RCAP2L
Value
Actual
Baud
%
Error
9600
1600
1200
1200
12.58
12.58
12.58
1.57
1
1
1
1
–7 (F9H)
–27 (E5H)
–55 (C9H)
–7 (F9H)
9362
1627
1192
1170
2.5
1.1
0.7
2.5
19200
9600
1600
1200
9600
1600
1200
12.58
12.58
12.58
12.58
1.57
1.57
1.57
–1 (FFH)
–1 (FFH)
–1 (FFH)
–2 (FEH)
–1 (FFH)
–1 (FFH)
–1 (FFH)
–20 (ECH)
–41 (D7H)
–164 (5CH)
–72 (B8H)
–5 (FBH)
–20 (ECH)
–41 (D7H)
19661
9591
2398
1199
9830
1658
1199
2.4
0.1
0.1
0.1
2.4
2.4
0.1
TIMER 1
OVERFLOW
2
OSC. FREQ. IS DIVIDED BY 2, NOT 12.
0
CORE
CLK*
T2
PIN
2
C/ T2 = 0
SMOD
TL2
(8 BITS)
TH2
(8 BITS)
TIMER 2
OVERFLOW
0
RCLK
16
1
NOTE AVAILABILITY OF ADDITIONAL
EXTERNAL INTERRUPT
RELOAD
RCAP2L
T2EX
PIN
EXF 2
RCAP2H
TIMER 2
INTERRUPT
CONTROL
EXEN2
*THE CORE CLOCK IS THE OUTPUT OF THE PLL (SEE THE ON-CHIP PLL SECTION)
Figure 56. Timer 2, UART Baud Rates
REV. A
1
C/ T2 = 1
TR2
TRANSITION
DETECTOR
1
CONTROL
–59–
RX
CLOCK
0
TCLK
16
TX
CLOCK
ADuC836
BAUD RATE GENERATION USING TIMER 3
The high integer dividers in a UART block means that high
speed baud rates are not always possible using some particular
crystals, e.g., using a 12 MHz crystal, a baud rate of 115200 is
not possible. To address this problem, the ADuC836 has added
a dedicated baud rate timer (Timer 3) specifically for generating
highly accurate baud rates.
Timer 3 can be used instead of Timer 1 or Timer 2 for generating
very accurate high speed UART baud rates including 115200 and
230400. Timer 3 also allows a much wider range of baud rates to
be obtained. In fact, every desired bit rate from 12 bits to 393216
bits can be generated to within an error of ±0.8%. Timer 3 also
frees up the other three timers allowing them to be used for different applications. A block diagram of Timer 3 is shown in
Figure 57.
CORE
CLK*
FRACTIONAL
DIVIDER
TIMER 1/TIMER 2
TX CLOCK (FIG 44)
T 3FD =
1
1
2 × fCORE
2
DIV
0
RX
CLOCK
0
− 64
DIV = log (12582912/32 × 115200) / log 2 = 1.77 = 1
(
Two SFRs (T3CON and T3FD) are used to control Timer 3.
T3CON is the baud rate control SFR, allowing Timer 3 to be
used to set up the UART baud rate, and setting up the binary
divider (DIV).
Table XXXIII. T3CON SFR Bit Designations
)
T 3FD = (2 × 12.582912) 21 × 115200 − 64 = 45.22 = 2Dh
TX CLOCK
*THE CORE CLOCK IS THE OUTPUT OF THE PLL (SEE THE ON-CHIP PLL SECTION)
Figure 57. Timer 3, UART Baud Rates
2 × fCORE
2DIV × (T 3FD + 64)
For a baud rate of 115200 while operating from the maximum
core frequency (CD = 0), we have:
T3EN
T3 RX/TX
CLOCK
× Baud Rate
Actual Baud Rate =
TIMER 1/TIMER 2
RX CLOCK (FIG 44)
2DIV
16
T3FD is the fractional divider ratio required to achieve the
required baud rate. We can calculate the appropriate value for
T3FD using the following formula. Note that the T3FD should
be rounded to the nearest integer.
Once the values for DIV and T3FD are calculated, the actual
baud rate can be calculated using the following formula:
2
(1 + T3FD/64)
The appropriate value to write to the DIV2-1-0 bits can be calculated using the following formula where fCORE is the output of
the PLL, as described in the On-Chip PLL section. Note that the
DIV value must be rounded down.


fCORE
log 

 32 × Baud Rate 
DIV =
log (2)
Therefore, the actual baud rate is 115439 bits.
Table XXXIV. Commonly Used Baud Rates Using Timer 3
Ideal
Baud
CD
DIV
T3CON
T3FD
%
Error
230400
0
0
80H
2DH
0.2
Bit
Name
Description
115200
115200
0
1
1
0
81H
80H
2DH
2DH
0.2
0.2
7
T3EN
Set to enable Timer 3 to generate the baud rate.
When set PCON.7, T2CON.4 and T2CON.5
are ignored. Cleared to let the baud rate be
generated as per a standard 8052.
57600
57600
57600
0
1
2
2
1
0
82H
81H
80H
2DH
2DH
2DH
0.2
0.2
0.2
6
–––
Reserved for Future Use
5
–––
Reserved for Future Use
4
–––
Reserved for Future Use
3
–––
Reserved for Future Use
38400
38400
38400
38400
0
1
2
3
3
2
1
0
83H
82H
81H
80H
12H
12H
12H
12H
0.1
0.1
0.1
0.1
2
DIV2
Binary Divider Factor
1
DIV1
DIV2 DIV1 DIV0 Bin Divider
0
DIV0
0
0
0
0
1
1
1
1
19200
19200
19200
19200
19200
0
1
2
3
4
4
3
2
1
0
84H
83H
82H
81H
80H
12H
12H
12H
12H
12H
0.1
0.1
0.1
0.1
0.1
9600
9600
9600
9600
9600
9600
38400
0
1
2
3
4
5
0
5
4
3
2
1
0
3
85H
84H
83H
82H
81H
80H
83H
12H
12H
12H
12H
12H
12H
12H
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
1
2
4
8
16
32
64
128
–60–
REV. A
ADuC836
INTERRUPT SYSTEM
The ADuC836 provides a total of 11 interrupt sources with two priority levels. The control and configuration of the interrupt system
are carried out through three interrupt-related SFRs: the IE (Interrupt Enable) Register, IP (Interrupt Priority Register), and IEIP2
(Secondary Interrupt Enable/Priority SFR) Registers. Their bit definitions are given in the Tables XXXV to XXXVII.
IE
Interrupt Enable Register
SFR Address
Power-On Default Value
Bit Addressable
A8H
00H
Yes
Table XXXV. IE SFR Bit Designations
Bit
Name
Description
7
6
5
4
3
2
1
0
EA
EADC
ET2
ES
ET1
EX1
ET0
EX0
Written by User to Enable 1 or Disable 0 All Interrupt Sources
Written by User to Enable 1 or Disable 0 ADC Interrupt
Written by User to Enable 1 or Disable 0 Timer 2 Interrupt
Written by User to Enable 1 or Disable 0 UART Serial Port Interrupt
Written by User to Enable 1 or Disable 0 Timer 1 Interrupt
Written by User to Enable 1 or Disable 0 External Interrupt 1
Written by User to Enable 1 or Disable 0 Timer 0 Interrupt
Written by User to Enable 1 or Disable 0 External Interrupt 0
IP
Interrupt Priority Register
SFR Address
Power-On Default Value
Bit Addressable
B8H
00H
Yes
Table XXXVI. IP SFR Bit Designations
Bit
Name
Description
7
6
5
4
3
2
1
0
–––
PADC
PT2
PS
PT1
PX1
PT0
PX0
Reserved for Future Use
Written by User to Select ADC Interrupt Priority (1 = High; 0 = Low)
Written by User to Select Timer 2 Interrupt Priority (1 = High; 0 = Low)
Written by User to Select UART Serial Port Interrupt Priority (1 = High; 0 = Low)
Written by User to Select Timer 1 Interrupt Priority (1 = High; 0 = Low)
Written by User to Select External Interrupt 1 Priority (1 = High; 0 = Low)
Written by User to Select Timer 0 Interrupt Priority (1 = High; 0 = Low)
Written by User to Select External Interrupt 0 Priority (1 = High; 0 = Low)
IEIP2
Secondary Interrupt Enable and
Priority Register
SFR Address
Power-On Default Value
Bit Addressable
A9H
A0H
No
Table XXXVII. IEIP2 SFR Bit Designations
Bit
Name
Description
7
6
5
4
3
2
1
0
–––
PTI
PPSM
PSI
–––
ETI
EPSM
ESI
Reserved for Future Use
Written by User to Select TIC Interrupt Priority (1 = High; 0 = Low)
Written by User to Select Power Supply Monitor Interrupt Priority (1 = High; 0 = Low)
Written by User to Select SPI/I2C Serial Port Interrupt Priority (1 = High; 0 = Low)
Reserved. This bit must be 0.
Written by User to Enable 1 or Disable 0 TIC Interrupt
Written by User to Enable 1 or Disable 0 Power Supply Monitor Interrupt
Written by User to Enable 1 or Disable 0 SPI/I2C Serial Port Interrupt
REV. A
–61–
ADuC836
Interrupt Priority
Interrupt Vectors
The Interrupt Enable registers are written by the user to enable
individual interrupt sources, while the Interrupt Priority registers
allow the user to select one of two priority levels for each interrupt. An interrupt of a high priority may interrupt the service
routine of a low priority interrupt, and if two interrupts of different priority occur at the same time, the higher level interrupt will
be serviced first. An interrupt cannot be interrupted by another
interrupt of the same priority level. If two interrupts of the same
priority level occur simultaneously, a polling sequence is used to
determine which interrupt is serviced first. The polling sequence
is shown in Table XXXVIII.
When an interrupt occurs, the program counter is pushed onto
the stack and the corresponding interrupt vector address is loaded
into the program counter. The interrupt vector addresses are
shown in Table XXXIX.
Table XXXIX. Interrupt Vector Addresses
Table XXXVIII. Priority within an Interrupt Level
Source
Priority
Description
PSMI
WDS
IE0
RDY0/RDY1
TF0
IE1
TF1
ISPI/I2CI
RI + TI
TF2 + EXF2
TII
1 (Highest)
2
3
4
5
6
7
8
9
10
11 (Lowest)
Power Supply Monitor Interrupt
Watchdog Interrupt
External Interrupt 0
ADC Interrupt
Timer/Counter 0 Interrupt
External Interrupt 1
Timer/Counter 1 Interrupt
SPI Interrupt
Serial Interrupt
Timer/Counter 2 Interrupt
Time Interval Counter Interrupt
–62–
Source
Vector Address
IE0
TF0
IE1
TF1
RI + TI
TF2 + EXF2
RDY0/RDY1 (ADC)
ISPI/I2CI
PSMI
TII
WDS (WDIR = 1)*
0003H
000BH
0013H
001BH
0023H
002BH
0033H
003BH
0043H
0053H
005BH
*The watchdog can be configured to generate an interrupt instead of
a reset when it times out. This is used for logging errors or examining
the internal status of the microcontroller core to understand, from
a software debug point of view, why a watchdog timeout occurred.
The watchdog interrupt is slightly different from the normal interrupts in that its priority level is always set to 1 and it is not possible
to disable the interrupt via the global disable bit (EA) in the IE SFR.
This is done to ensure that the interrupt will always be responded
to if a watchdog timeout occurs. The watchdog will only produce an
interrupt if the watchdog timeout is greater than zero.
REV. A
ADuC836
ADuC836 HARDWARE DESIGN CONSIDERATIONS
This section outlines some of the key hardware design considerations that must be addressed when integrating the ADuC836
into any hardware system.
External Memory Interface
In addition to its internal program and data memories, the
ADuC836 can access up to 64 Kbytes of external program memory
(ROM, PROM, and so on) and up to 16 Mbytes of external data
memory (SRAM).
Though both external program memory and external data memory
are accessed using some of the same pins, the two are completely
independent of each other from a software point of view. For
example, the chip can read/write external data memory while
executing from external program memory.
Figure 59 shows a hardware configuration for accessing up to
64 Kbytes of external data memory. This interface is standard to
any 8051 compatible MCU.
ADuC836
To select from which code space (internal or external program
memory) to begin executing code, tie the EA (external access)
pin high or low, respectively. When EA is high (pulled up to VDD),
user program execution will start at Address 0 in the internal
62 Kbytes Flash/EE code space. When EA is low (tied to ground)
user program execution will start at Address 0 in the external
code space. When executing from internal code space, accesses
to the program space above F7FFH (62 Kbytes) will be read as
NOP instructions.
ADuC836
D0–D7
(DATA)
P0
LATCH
A0–A7
ALE
Note that a second very important function of the EA pin is
described in the Single Pin Emulation Mode section.
External program memory (if used) must be connected to the
ADuC836, as illustrated in Figure 58. Sixteen I/O lines (Ports 0
and 2) are dedicated to bus functions during external program
memory fetches. Port 0 (P0) serves as a multiplexed address/data
bus. It emits the low byte of the program counter (PCL) as
an address, and then goes into a high impedance input state
awaiting the arrival of the code byte from the program memory.
During the time that the low byte of the program counter is valid
on P0, the signal ALE (Address Latch Enable) clocks this byte
into an external address latch. Meanwhile, Port 2 (P2) emits the
high byte of the program counter (PCH), and PSEN strobes the
EPROM and the code byte is read into the ADuC836.
SRAM
P2
A8–A15
RD
OE
WR
WE
Figure 59. External Data Memory Interface
(64 Kbytes Address Space)
If access to more than 64 Kbytes of RAM is desired, a feature
unique to the MicroConverter allows addressing up to 16 Mbytes
of external RAM simply by adding an additional latch, as illustrated in Figure 60.
SRAM
ADuC836
D0–D7
(DATA)
P0
LATCH
A0–A7
ALE
EPROM
LATCH
A8–A15
P2
D0–D7
(INSTRUCTION)
P0
LATCH
A0–A7
A16–A23
ALE
P2
PSEN
RD
OE
WR
WE
A8–A15
Figure 60. External Data Memory Interface
(16 Mbytes Address Space)
OE
Figure 58. External Program Memory Interface
Note that program memory addresses are always 16 bits wide,
even in cases where the actual amount of program memory used
is less than 64 Kbytes. External program execution sacrifices
two of the 8-bit ports (P0 and P2) to the function of addressing
the program memory. While executing from external program
memory, Ports 0 and 2 can be used simultaneously for read/write
access to external data memory, but not for general-purpose I/O.
In either implementation, Port 0 (P0) serves as a multiplexed
address/data bus. It emits the low byte of the data pointer (DPL)
as an address, which is latched by ALE prior to data being placed
on the bus by the ADuC836 (write operation) or by the external
data memory (read operation). Port 2 (P2) provides the data
pointer page byte (DPP) to be latched by ALE, followed by the
data pointer high byte (DPH). If no latch is connected to P2,
DPP is ignored by the SRAM, and the 8051 standard of 64 Kbyte
external data memory access is maintained.
Detailed timing diagrams of external program and data memory
read and write access can be found in the Timing Specifications
section.
REV. A
–63–
ADuC836
Power Supplies
The ADuC836’s operational power supply voltage range is 2.7 V
to 5.25 V. Although the guaranteed data sheet specifications are
given only for power supplies within 2.7 V to 3.6 V or +5% of the
nominal 5 V level, the chip will function equally well at any power
supply level between 2.7 V and 5.25 V.
Separate analog and digital power supply pins (AVDD and DVDD,
respectively) allow AVDD to be kept relatively free of noisy digital
signals that are often present on the system DVDD line. In this mode,
the part can also operate with split supplies, that is, using different
voltage supply levels for each supply. For example, this means that
the system can be designed to operate with a DVDD voltage level of
3 V while the AVDD level can be at 5 V, or vice-versa if required. A
typical split-supply configuration is shown in Figure 61.
ANALOG SUPPLY
DIGITAL SUPPLY
10F
10F
+
–
20
34
+
–
ADuC836
DVDD
AVDD
5
0.1F
Notice that in Figures 61 and 62, a large value (10 F) reservoir
capacitor sits on DVDD and a separate 10 F capacitor sits on
AVDD. Also, local decoupling capacitors (0.1 F) are located at
each VDD pin of the chip. As per standard design practice, be sure
to include all of these capacitors and ensure the smaller capacitors
are closest to each VDD pin with lead lengths as short as possible.
Connect the ground terminal of each of these capacitors directly to
the underlying ground plane. Finally, it should also be noticed that,
at all times, the analog and digital ground pins on the ADuC836
should be referenced to the same system ground reference point.
Power-On Reset (POR) Operation
An internal POR (Power-On Reset) is implemented on the
ADuC836. For DVDD below 2.45 V, the internal POR will hold
the ADuC836 in reset. As DVDD rises above 2.45 V, an internal
timer will time out for typically 128 ms before the part is
released from reset. The user must ensure that the power supply
has reached a stable 2.7 V minimum level by this time. Likewise
on power-down, the internal POR will hold the ADuC836 in
reset until the power supply has dropped below 1 V. Figure 63
illustrates the operation of the internal POR in detail.
48
0.1F
DVDD
21
35
DGND
AGND
6
2.45V TYP
1.0V TYP
128ms TYP
128ms TYP
1.0V TYP
47
INTERNAL
CORE RESET
Figure 61. External Dual-Supply Connections
As an alternative to providing two separate power supplies, AVDD
can be kept quiet by placing a small series resistor and/or ferrite
bead between it and DVDD, and then decoupling AVDD separately
to ground. An example of this configuration is shown in Figure 62.
In this configuration, other analog circuitry (such as op amps,
voltage reference, and so on) can be powered from the AVDD
supply line as well.
DIGITAL SUPPLY
+
–
10F
BEAD
20
34
1.6
10F
ADuC836
DVDD
AVDD
5
AGND
6
0.1F
48
0.1F
21
35
47
DGND
Figure 63. Internal Power-on-Reset Operation
Power Consumption
The DVDD power supply current consumption is specified in
normal, idle, and power-down modes. The AVDD power supply
current is specified with the analog peripherals disabled. The
normal mode power consumption represents the current drawn
from DVDD by the digital core. The other on-chip peripherals
(watchdog timer, power supply monitor, and so on) consume
negligible current and are therefore lumped in with the normal
operating current here. Of course, the user must add any currents
sourced by the parallel and serial I/O pins, and those sourced
by the DAC in order to determine the total current needed at the
ADuC836’s DVDD and AVDD supply pins. Also, current drawn
from the DVDD supply will increase by approximately 5 mA during
Flash/EE erase and program cycles.
Figure 62. External Single-Supply Connections
–64–
REV. A
ADuC836
Power Saving Modes
Wake-Up from Power-Down Latency
Setting the Idle and Power-Down Mode Bits, PCON.0 and
PCON.1, respectively, in the PCON SFR described in Table II
allows the chip to be switched from Normal mode into Idle
mode, and also into full Power-Down mode.
Even with the 32 kHz crystal enabled during power-down, the PLL
will take some time to lock after a wake-up from power-down. Typically, the PLL will take about 1 ms to lock. During this time, code
will execute, but not at the specified frequency. Some operations
require an accurate clock, for example, UART communications,
to achieve specified 50 Hz/60 Hz rejection from the ADCs. The
following code may be used to wait for the PLL to lock:
In Idle mode, the oscillator continues to run, but the core clock
generated from the PLL is halted. The on-chip peripherals
continue to receive the clock and remain functional. The CPU
status is preserved with the stack pointer, program counter, and
all other internal registers maintain their data during Idle mode.
Port pins and DAC output pins also retain their states, and ALE
and PSEN outputs go high in this mode. The chip will recover
from Idle mode upon receiving any enabled interrupt, or upon
receiving a hardware reset.
WAITFORLOCK:
MOV A, PLLCON
JNB ACC.6, WAITFORLOCK
If the crystal has been powered down during power-down, there
is an additional delay associated with the startup of the crystal
oscillator before the PLL can lock. 32 kHz crystals are inherently
slow to oscillate, typically taking about 150 ms. Once again, during
this time before lock, code will execute, but the exact frequency
of the clock cannot be guaranteed. Again for any timing sensitive
operations, it is recommended to wait for lock using the lock bit
in PLLCON, as shown in the code above.
In Power-Down mode, both the PLL and the clock to the core are
stopped. The on-chip oscillator can be halted or can continue to
oscillate, depending on the state of the oscillator power-down bit
(OSC_PD) in the PLLCON SFR. The TIC, being driven directly
from the oscillator, can also be enabled during power-down. All
other on-chip peripherals, however, are shut down. Port pins retain
their logic levels in this mode, but the DAC output goes to a high
impedance state (three-state) while ALE and PSEN outputs are
held low. During full Power-Down mode with the oscillator and
wake-up timer running, the ADuC836 typically consumes a total
of 15 A. There are five ways of terminating Power-Down mode:
Grounding and Board Layout Recommendations
As with all high resolution data converters, special attention must
be paid to grounding and PC board layout of ADuC836 based
designs in order to achieve optimum performance from the ADCs
and DAC.
Although the ADuC836 has separate pins for analog and digital
ground (AGND and DGND), the user must not tie these to two
separate ground planes unless the two ground planes are connected together very close to the ADuC836, as illustrated in the
simplified example of Figure 64a. In systems where digital and
analog ground planes are connected together somewhere else
(at the system’s power supply, for example), they cannot be connected again near the ADuC836 since a ground loop would result.
In these cases, tie the ADuC836’s AGND and DGND pins all to
the analog ground plane, as illustrated in Figure 64b. In systems
with only one ground plane, ensure that the digital and analog components are physically separated onto separate halves of the board
such that digital return currents do not flow near analog circuitry
and vice versa. The ADuC836 can then be placed between the
digital and analog sections, as illustrated in Figure 64c.
Asserting the RESET Pin (Pin 15)
Returns to Normal mode. All registers are set to their reset default
value and program execution starts at the reset vector once the
RESET pin is deasserted.
Cycling Power
All registers are set to their default state and program execution
starts at the reset vector approximately 128 ms later.
Time Interval Counter (TIC) Interrupt
If the OSC_PD bit in the PLLCON SFR is clear, the 32 kHz
oscillator will remain powered up even in Power-Down mode.
If the Time Interval Counter (Wakeup/RTC timer) is enabled,
a TIC interrupt will wake the ADuC836 up from Power-Down
mode. The CPU services the TIC interrupt. The RETI at the end
of the TIC ISR will return the core to the instruction after the
one that enabled power-down.
SPI Interrupt
If the SERIPD bit in the PCON SFR is set, then an SPI interrupt,
if enabled, will wake up the ADuC836 from Power-Down mode.
The CPU services the SPI interrupt. The RETI at the end of the
ISR will return the core to the instruction after the one that enabled
power-down.
INT0 Interrupt
If the INT0PD bit in the PCON SFR is set, an external interrupt 0,
if enabled, will wake up the ADuC836 from power-down. The
CPU services the SPI interrupt. The RETI at the end of the ISR
will return the core to the instruction after the one that enabled
power-down.
REV. A
In all of these scenarios, and in more complicated real-life applications, keep in mind the flow of current from the supplies and
back to ground. Make sure the return paths for all currents are as
close as possible to the paths the currents took to reach their destinations. For example, do not power components on the analog
side of Figure 64b with DVDD since that would force return currents from DVDD to flow through AGND. Also, try to avoid digital
currents flowing under analog circuitry, which could happen if
the user placed a noisy digital chip on the left half of the board
in Figure 64c. Whenever possible, avoid large discontinuities in
the ground plane(s) (such as those formed by a long trace on the
same layer), since they force return signals to travel a longer path.
And of course, make all connections directly to the ground plane
with little or no trace separating the pin from its via to ground.
–65–
ADuC836
a.
PLACE DIGITAL
COMPONENTS
HERE
PLACE ANALOG
COMPONENTS
HERE
AGND
DGND
The CHIPID SFR is a read-only register located at SFR address
C2H. The upper nibble of this SFR designates the MicroConverter
within the - ADC family. User software can read this SFR to
identify the host MicroConverter and thus execute slightly different code if required. The CHIPID SFR reads as follows for the
- ADC family of MicroConverter products.
ADuC836
ADuC834
ADuC824
ADuC816
b.
PLACE ANALOG
COMPONENTS
HERE
PLACE DIGITAL
COMPONENTS
HERE
AGND
c.
DGND
PLACE ANALOG
COMPONENTS
HERE
PLACE DIGITAL
COMPONENTS
HERE
GND
Figure 64. System Grounding Schemes
If the user plans to connect fast logic signals (rise/fall time < 5 ns)
to any of the ADuC836’s digital inputs, add a series resistor to
each relevant line to keep rise and fall times longer than 5 ns at the
ADuC836 input pins. A value of 100  or 200  is usually sufficient to prevent high speed signals from coupling capacitively into
the ADuC836 and affecting the accuracy of ADC conversions.
Clock Oscillator
As described earlier, the core clock frequency for the ADuC836
is generated from an on-chip PLL that locks onto a multiple (384
times) of 32.768 kHz. The latter is generated from an internal
clock oscillator. To use the internal clock oscillator, connect a
32.768 kHz parallel resonant crystal between the XTAL1 and
XTAL2 pins (32 and 33), as shown in Figure 65.
As shown in the typical external crystal connection diagram in
Figure 65, two internal 12 pF capacitors are provided on-chip.
These are connected internally, directly to the XTAL1 and
XTAL2 pins, and the total input capacitances at both pins is
detailed in the Specifications table. The value of the total load
capacitance required for the external crystal should be the value
recommended by the crystal manufacturer for use with that
specific crystal. In many cases, because of the on-chip capacitors,
additional external load capacitors will not be required.
ADuC836
XTAL1
32
32.768kHz
12pF
33
ADuC836 System Self-Identification
In some hardware designs, it may be an advantage for the software
running on the ADuC836 target to identify the host MicroConverter. For example, code running on the ADuC836 may also
be used with the ADuC824 or the ADuC816, and is required to
operate differently.
CHIPID = 3xH
CHIPID = 2xH
CHIPID = 0xH
CHIPID = 1xH
XTAL2
12pF
TO INTERNAL
PLL
Figure 65. External Parallel Resonant Crystal
Connections Other Hardware Considerations
To facilitate in-circuit programming plus in-circuit debug and
emulation options, users will want to implement some simple
connection points in their hardware that will allow easy access to
Download, Debug, and Emulation modes.
–66–
REV. A
ADuC836
OTHER HARDWARE CONSIDERATIONS
In-Circuit Serial Download Access
Nearly all ADuC836 designs will want to take advantage of the
in-circuit reprogrammability of the chip. This is accomplished
by a connection to the ADuC836’s UART, which requires an
external RS-232 chip for level translation if downloading code
from a PC. Basic configuration of an RS-232 connection is illustrated in Figure 66 with a simple ADM3202 based circuit. If users
would rather not include an RS-232 chip onto the target board,
refer to the application note, uC006–A 4-Wire UART-to-PC Interface
available at www.analog.com/microconverter, for a simple (and
zero-cost-per-board) method of gaining in-circuit serial download
access to the ADuC836.
In addition to the basic UART connections, users will also need
a way to trigger the chip into Download mode. This is accomplished via a 1 k pull-down resistor that can be jumpered onto
the PSEN pin, as shown in Figure 66. To get the ADuC836 into
Download mode, simply connect this jumper and power-cycle the
device (or manually reset the device, if a manual reset button is
available), and it will be ready to receive a new program serially.
With the jumper removed, the device will power on in Normal
mode (and run the program) whenever power is cycled or RESET
is toggled.
Note that PSEN is normally an output (as described in the External Memory Interface section) and that it is sampled as an input
only on the falling edge of RESET (i.e., at power-up or upon an
external manual reset). Note also that if any external circuitry
unintentionally pulls PSEN low during power-up or reset events,
it could cause the chip to enter Download mode and therefore fail
to begin user code execution as it should. To prevent this, ensure
REV. A
that no external signals are capable of pulling the PSEN pin low,
except for the external PSEN jumper itself.
Embedded Serial Port Debugger
From a hardware perspective, entry to Serial Port Debug mode is
identical to the serial download entry sequence described above.
In fact, both Serial Download and Serial Port Debug modes can
be thought of as essentially one mode of operation used in two
different ways.
Note that the serial port debugger is fully contained on the
ADuC836 device, (unlike ROM monitor type debuggers) and
therefore no external memory is needed to enable in-system
debug sessions.
Single-Pin Emulation Mode
Also built into the ADuC836 is a dedicated controller for single-pin
in-circuit emulation (ICE) using standard production ADuC836
devices. In this mode, emulation access is gained by connection to
a single pin, the EA pin. Normally, this pin is hard-wired either
high or low to select execution from internal or external program
memory space, as described earlier. To enable single-pin emulation mode, however, users will need to pull the EA pin high
through a 1 k resistor, as shown in Figure 66. The emulator
will then connect to the 2-pin header also shown in Figure 66.
To be compatible with the standard connector that comes
with the single-pin emulator available from Accutron Limited
(www.accutron.com), use a 2-pin 0.1-inch pitch Friction Lock
header from Molex (www.molex.com) such as their part number
22-27-2021. Be sure to observe the polarity of this header. As
represented in Figure 66, when the Friction Lock tab is at the
right, the ground pin should be the lower of the two pins (when
viewed from the top).
–67–
ADuC836
Typical System Configuration
its resistance. This differential voltage is routed directly to the
positive and negative inputs of the primary ADC (AIN1, AIN2,
respectively). The same current that excited the RTD also flows
through a series resistance RREF, generating a ratiometric voltage
reference VREF. The ratiometric voltage reference ensures that
variations in the excitation current do not affect the measurement
system as the input voltage from the RTD and reference voltage
across RREF vary ratiometrically with the excitation current. Resistor RREF must, however, have a low temperature coefficient to
avoid errors in the reference voltage over temperature. RREF must
also be large enough to generate at least a 1 V voltage reference.
A typical ADuC836 configuration is shown in Figure 66. It summarizes some of the hardware considerations discussed in the
previous paragraphs.
Figure 66 also includes connections for a typical analog measurement application of the ADuC836, namely an interface to an
RTD (Resistive Temperature Device). The arrangement shown is
commonly referred to as a 4-wire RTD configuration.
Here, the on-chip excitation current sources are enabled to
excite the sensor. The excitation current flows directly through
the RTD, generating a voltage across the RTD proportional to
DOWNLOAD/DEBUG
ENABLE JUMPER
(NORMALLY OPEN)
DVDD
1k
DVDD
49
48
45
44
43
42
P1.2/IEXC1/DAC
200A/400A
EXCITATION
CURRENT
AVDD
39
38
36
AVDD
DVDD
DGND 35
AGND
DVDD 34
ADuC836
REFIN–
XTAL2 33
XTAL1 32
REFIN+
RREF
5.6k
40
2-PIN HEADER FOR
EMULATION ACCESS
(NORMALLY OPEN)
37
P1.3/AIN5/DAC
RTD
41
EA
50
46
PSEN
51
DVDD
52
47
DGND
1k
P1.4/AIN1
31
P1.5/AIN2
30
32.768kHz
DVDD
28
DGND
DVDD
TXD
RXD
RESET
29
27
NOT CONNECTED IN THIS EXAMPLE
DVDD
ALL CAPACITORS IN THIS EXAMPLE ARE
0.1F CERAMIC CAPACITORS.
RS232 INTERFACE*
ADM3202
C1+
V+
VCC
STANDARD D-TYPE
SERIAL COMMS
CONNECTOR TO
PC HOST
GND
1
C1–
T1OUT
2
C2+
R1IN
3
C2–
R1OUT
4
V–
T1IN
5
T2OUT
T2IN
6
R2OUT
7
R2IN
8
9
*EXTERNAL UART TRANSCEIVER INTEGRATED IN SYSTEM OR AS
PART OF AN EXTERNAL DONGLE AS DESCRIBED IN uC006.
Figure 66. Typical System Configuration
–68–
REV. A
ADuC836
QUICKSTART DEVELOPMENT SYSTEM
The QuickStart Development System is a full featured, low cost
development tool suite supporting the ADuC836. The system
consists of the following PC based (Windows® compatible) hardware and software development tools:
Hardware:
ADuC836 Evaluation Board
and Serial Port Cable
Code Development:
8051 Assembler
Code Functionality:
ADSIM, Windows
MicroConverter Code
Simulator
In-Circuit Code Download:
Serial Downloader
In-Circuit Debugger/Emulator: Serial Port/Single Pin
Debugger/Emulator with
Assembly and C Source
Debug
Miscellaneous Other:
CD-ROM Documentation
and Two Additional
Prototype Devices
Figure 67 shows the typical components of a QuickStart Development System while Figure 68 shows a typical debug session. A
brief description of some of the software tools’ components in the
QuickStart Development System follows.
Download—In Circuit Downloader
The Serial Downloader is a software program that allows the user
to serially download an assembled program (Intel Hex format file)
to the on-chip program Flash memory via the serial COM1 port on
a standard PC. Application Note uC004 details this serial download
protocol and is available from www.analog.com/microconverter.
Debugger/Emulator—In-Circuit Debugger/Emulator
The Debugger/Emulator is a Windows application that allows the
user to debug code execution on silicon using the MicroConverter
UART serial port or via a single pin to provide nonintrusive
debug. The debugger provides access to all on-chip peripherals
during a typical debug session, including single-step and multiple
break-point code execution control. C source and assembly level
debug are both possible with the emulator.
ADSIM—Windows Simulator
The Simulator is a Windows application that fully simulates the
MicroConverter functionality including ADC and DAC peripherals. The simulator provides an easy-to-use, intuitive, interface to
the MicroConverter functionality and integrates many standard
debug features including multiple breakpoints, single stepping,
and code execution trace capability. This tool can be used both
as a tutorial guide to the part as well as an efficient way to prove
code functionality before moving to a hardware platform.
Figure 68. Typical Debug Session
Figure 67. Components of the QuickStart Development
System
REV. A
–69–
ADuC836
TIMING SPECIFICATIONS1, 2, 3
(AVDD = 2.7 V to 3.6 V or 4.75 V to 5.25 V, DVDD = 2.7 V to 3.6 V or 4.75 V to 5.25 V;
all specifications TMIN to TMAX, unless otherwise noted.)
Parameter
32.768 kHz External Crystal
Typ
Max
Min
CLOCK INPUT (External Clock Driven XTAL1)
tCK
XTAL1 Period
tCKL
XTAL1 Width Low
tCKH
XTAL1 Width High
tCKR
XTAL1 Rise Time
tCKF
XTAL1 Fall Time
1/tCORE
ADuC836 Core Clock Frequency4
tCORE
ADuC836 Core Clock Period5
tCYC
ADuC836 Machine Cycle Time6
30.52
6.26
6.26
9
9
0.098
s
s
s
s
s
MHz
s
s
12.58
0.636
7.6
0.95
Unit
122.45
NOTES
1
AC inputs during testing are driven at DVDD – 0.5 V for a Logic 1, and 0.45 V for a Logic 0. Timing measurements are made at VIH min for a Logic 1, and VIL max for a
Logic 0, as shown in Figure 70.
2
For timing purposes, a port pin is no longer floating when a 100 mV change from load voltage occurs. A port pin begins to float when a 100 mV change from the loaded
VOH/VOL level occurs, as shown in Figure 70.
3
CLOAD for Port 0, ALE, PSEN outputs = 100 pF; CLOAD for all other outputs = 80 pF, unless otherwise noted.
4
ADuC836 internal PLL locks onto a multiple (384 times) the external crystal frequency of 32.768 kHz to provide a stable 12.583 MHz internal clock for the system.
The core can operate at this frequency or at a binary submultiple called Core_Clk, selected via the PLLCON SFR.
5
This number is measured at the default Core_Clk operating frequency of 1.57 MHz.
6
ADuC836 Machine Cycle Time is nominally defined as 12/Core_Clk.
tCKR
tCKH
tCKL
tCKF
tCK
Figure 69. XTAL1 Input
DVDD – 0.5V
0.45V
0.2DVDD + 0.9V
TEST POINTS
0.2DVDD – 0.1V
VLOAD – 0.1V
VLOAD
VLOAD + 0.1V
TIMING
REFERENCE
POINTS
VLOAD – 0.1V
VLOAD
VLOAD + 0.1V
Figure 70. Timing Waveform Characteristics
–70–
REV. A
ADuC836
Parameter
EXTERNAL PROGRAM MEMORY
tLHLL
ALE Pulsewidth
tAVLL
Address Valid to ALE Low
tLLAX
Address Hold after ALE Low
tLLIV
ALE Low to Valid Instruction In
tLLPL
ALE Low to PSEN Low
tPLPH
PSEN Pulsewidth
tPLIV
PSEN Low to Valid Instruction In
tPXIX
Input Instruction Hold after PSEN
tPXIZ
Input Instruction Float after PSEN
tAVIV
Address to Valid Instruction In
tPLAZ
PSEN Low to Address Float
tPHAX
Address Hold after PSEN High
12.58 MHz Core_Clk
Min
Max
Min
119
39
49
2tCORE – 40
tCORE – 40
tCORE – 30
218
49
193
tCORE – 30
3tCORE – 45
133
0
0
54
292
25
0
Variable Core_Clk
Max
0
tLHLL
ALE (O)
tPLPH
tLLPL
tLLIV
tPLIV
PSEN (O)
PORT 0 (I/O)
tPXIZ
tPLAZ
tLLAX
tPXIX
PCL
(OUT)
INSTRUCTION
(IN)
tAVIV
PORT 2 (O)
tPHAX
PCH
Figure 71. External Program Memory Read Cycle
REV. A
–71–
3tCORE – 105
tCORE – 25
5tCORE – 105
25
CORE_CLK
tAVLL
4tCORE – 100
Unit
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ADuC836
Parameter
EXTERNAL DATA MEMORY READ CYCLE
tRLRH
RD Pulsewidth
tAVLL
Address Valid after ALE Low
tLLAX
Address Hold after ALE Low
tRLDV
RD Low to Valid Data In
tRHDX
Data and Address Hold after RD
tRHDZ
Data Float after RD
tLLDV
ALE Low to Valid Data In
tAVDV
Address to Valid Data In
tLLWL
ALE Low to RD Low
tAVWL
Address Valid to RD Low
tRLAZ
RD Low to Address Float
tWHLH
RD High to ALE High
12.58 MHz Core_Clk
Min
Max
Min
377
39
44
6tCORE – 100
tCORE – 40
tCORE – 35
232
0
0
89
486
550
288
188
188
3tCORE – 50
4tCORE – 130
0
119
39
Variable Core_Clk
Max
tCORE – 40
5tCORE – 165
2tCORE – 70
8tCORE – 150
9tCORE – 165
3tCORE + 50
0
tCORE + 40
Unit
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
CORE_CLK
ALE (O)
tWHLH
PSEN (O)
tLLDV
tLLWL
tRLRH
RD (O)
tAVWL
tAVLL
PORT 0 (I/O)
tLLAX
tRLDV
tRHDX
tRHDZ
tRLAZ
A0–A7
(OUT)
DATA (IN)
tAVDV
PORT 2 (O)
A16–A23
A8–A15
Figure 72. External Data Memory Read Cycle
–72–
REV. A
ADuC836
Parameter
12.58 MHz Core_Clk
Min
Max
Min
EXTERNAL DATA MEMORY WRITE CYCLE
tWLWH
WR Pulsewidth
tAVLL
Address Valid after ALE Low
tLLAX
Address Hold after ALE Low
tLLWL
ALE Low to WR Low
tAVWL
Address Valid to WR Low
tQVWX
Data Valid to WR Transition
tQVWH
Data Setup before WR
tWHQX
Data and Address Hold after WR
tWHLH
WR High to ALE High
377
39
44
188
188
29
406
29
39
6tCORE – 100
tCORE – 40
tCORE – 35
3tCORE – 50
4tCORE – 130
tCORE – 50
7tCORE – 150
tCORE – 50
tCORE – 40
288
119
Variable Core_Clk
Max
CORE_CLK
ALE (O)
tWHLH
PSEN (O)
tLLWL
tWLWH
WR (O)
tAVWL
tAVLL
tLLAX
PORT 0 (O)
A0–A7
PORT 2 (O)
A16–A23
tQVWX
tWHQX
tQVWH
DATA
A8–A15
Figure 73. External Data Memory Write Cycle
REV. A
–73–
3tCORE + 50
tCORE + 40
Unit
ns
ns
ns
ns
ns
ns
ns
ns
ns
ADuC836
Parameter
12.58 MHz Core_Clk
Min
Typ
Max
UART TIMING (Shift Register Mode)
tXLXL
Serial Port Clock Cycle Time
tQVXH
Output Data Setup to Clock
tDVXH
Input Data Setup to Clock
tXHDX
Input Data Hold after Clock
tXHQX
Output Data Hold after Clock
662
292
0
42
0.95
Variable Core_Clk
Typ
Min
10tCORE – 133
2tCORE + 133
0
2tCORE – 117
12tCORE
Max
Unit
s
ns
ns
ns
ns
ALE (O)
tXLXL
TxD
(OUTPUT CLOCK)
01
67
SET RI
OR
SET TI
tQVXH
tXHQX
RxD
(OUTPUT DATA)
BIT 6
MSB
BIT 1
tDVXH
RxD
(INPUT DATA)
MSB
tXHDX
BIT 1
BIT 6
LSB
Figure 74. UART Timing in Shift Register Mode
–74–
REV. A
ADuC836
Parameter
Min
SPI MASTER MODE TIMING (CPHA = 1)
tSL
SCLOCK Low Pulsewidth*
tSH
SCLOCK High Pulsewidth*
tDAV
Data Output Valid after SCLOCK Edge
tDSU
Data Input Setup Time before SCLOCK Edge
tDHD
Data Input Hold Time after SCLOCK Edge
tDF
Data Output Fall Time
tDR
Data Output Rise Time
tSR
SCLOCK Rise Time
tSF
SCLOCK Fall Time
Typ
Max
630
630
100
100
50
10
10
10
10
25
25
25
25
Unit
ns
ns
ns
ns
ns
ns
ns
ns
ns
*Characterized under the following conditions:
Core clock divider bits CD2, CD1, and CD0 in PLLCON SFR set to 0, 1, and 1, respectively, i.e., core clock frequency = 1.57 MHz, and SPI bit rate selection bits
SPR1 and SPR0 in SPICON SFR are both set to 0.
SCLOCK
(CPOL = 0)
tSH
tSL
tSF
tSR
SCLOCK
(CPOL = 1)
tDAV
MOSI
tDOSU
tDF
MSB
MISO
MSB IN
tDSU
tDR
BITS 6–1
BITS 6–1
LSB
LSB IN
tDHD
Figure 75. SPI Master Mode Timing (CPHA = 1)
REV. A
–75–
ADuC836
Parameter
Min
SPI MASTER MODE TIMING (CPHA = 0)
tSL
SCLOCK Low Pulsewidth*
tSH
SCLOCK High Pulsewidth*
tDAV
Data Output Valid after SCLOCK Edge
tDOSU
Data Output Setup before SCLOCK Edge
tDSU
Data Input Setup Time before SCLOCK Edge
tDHD
Data Input Hold Time after SCLOCK Edge
tDF
Data Output Fall Time
tDR
Data Output Rise Time
tSR
SCLOCK Rise Time
tSF
SCLOCK Fall Time
Typ
Max
630
630
100
100
50
150
10
10
10
10
25
25
25
25
Unit
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
*Characterized under the following conditions:
1. Core clock divider bits CD2, CD1, and CD0 in PLLCON SFR set to 0, 1, and 1 respectively, i.e., core clock frequency = 1.57 MHz.
2. SPI bit rate selection bits SPR1 and SPR0 in SPICON SFR are both set to 0.
SCLOCK
(CPOL = 0)
tSH
tSL
tSR
SCLOCK
(CPOL = 1)
tDAV
tDF
MOSI
tDR
BITS 6–1
MSB
MISO
BITS 6–1
MSB IN
tDSU
tSF
LSB
LSB IN
tDHD
Figure 76. SPI Master Mode Timing (CPHA = 0)
–76–
REV. A
ADuC836
Parameter
Min
SPI SLAVE MODE TIMING (CPHA = 1)
tSS
SS to SCLOCK Edge
tSL
SCLOCK Low Pulsewidth
tSH
SCLOCK High Pulsewidth
tDAV
Data Output Valid after SCLOCK Edge
tDSU
Data Input Setup Time before SCLOCK Edge
tDHD
Data Input Hold Time after SCLOCK Edge
tDF
Data Output Fall Time
tDR
Data Output Rise Time
tSR
SCLOCK Rise Time
tSF
SCLOCK Fall Time
tSFS
SS High after SCLOCK Edge
Typ
0
Max
330
330
100
100
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
50
10
10
10
10
0
Unit
25
25
25
25
SS
tSFS
tSS
SCLOCK
(CPOL = 0)
tSL
tSH
tSR
tSF
SCLOCK
(CPOL = 1)
tDAV
tDF
MISO
MOSI
BITS 6–1
MSB
BITS 6–1
MSB IN
tDSU
tDR
tDHD
Figure 77. SPI Slave Mode Timing (CPHA = 1)
REV. A
–77–
LSB
LSB IN
ADuC836
Parameter
Min
SPI SLAVE MODE TIMING (CPHA = 0)
tSS
SS to SCLOCK Edge
tSL
SCLOCK Low Pulsewidth
tSH
SCLOCK High Pulsewidth
tDAV
Data Output Valid after SCLOCK Edge
tDSU
Data Input Setup Time before SCLOCK Edge
tDHD
Data Input Hold Time after SCLOCK Edge
tDF
Data Output Fall Time
tDR
Data Output Rise Time
tSR
SCLOCK Rise Time
tSF
SCLOCK Fall Time
tSSR
SS to SCLOCK Edge
tDOSS
Data Output Valid after SS Edge
tSFS
SS High after SCLOCK Edge
0
100
100
Typ
Max
330
330
Unit
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
50
10
10
10
10
25
25
25
25
50
20
0
SS
tSFS
tSS
SCLOCK
(CPOL = 0)
tSH
tSL
tSF
tSR
SCLOCK
(CPOL = 1)
tDAV
tDOSS
tDF
MISO
MOSI
MSB
MSB IN
tDSU
tDR
BITS 6–1
BITS 6–1
LSB
LSB IN
tDHD
Figure 78. SPI Slave Mode Timing (CPHA = 0)
–78–
REV. A
ADuC836
Parameter
Min
Max
Unit
2
I C-SERIAL INTERFACE TIMING
tL
SCLOCK Low Pulsewidth
tH
SCLOCK High Pulsewidth
tSHD
Start Condition Hold Time
tDSU
Data Setup Time
tDHD
Data Hold Time
tRSU
Setup Time for Repeated Start
tPSU
Stop Condition Setup Time
tBUF
Bus Free Time between a STOP
Condition and a START Condition
tR
Rise Time of Both SCLOCK and SDATA
tF
Fall Time of Both SCLOCK and SDATA
tSUP*
Pulsewidth of Spike Suppressed
4.7
4.0
0.6
100
µs
µs
µs
ns
µs
µs
µs
µs
0.9
0.6
0.6
1.3
300
300
50
ns
ns
ns
*Input filtering on both the SCLOCK and SDATA inputs surpresses noise spikes less than 50 ns.
tBUF
tSUP
SDATA (I/O)
MSB
tDSU
tPSU
LSB
tL
tR
tRSU
8
2-7
tF
tDHD
9
tSUP
1
S(R)
REPEATED
START
STOP
START
CONDITION CONDITION
Figure 79. I 2C Compatible Interface Timing
REV. A
MSB
tDSU
tH
1
PS
ACK
tDHD
tSHD
SCLK (I)
tR
–79–
tF
ADuC836
OUTLINE DIMENSIONS
52-Lead Metric Quad Flat Package [MQFP]
(S-52)
Dimensions shown in millimeters
14.15
13.90 SQ
13.65
2.45
MAX
39
27
40
SEATING
PLANE
C02991–0–4/03(A)
1.03
0.88
0.73
26
7.80
REF
10.20
10.00 SQ
9.80
TOP VIEW
(PINS DOWN)
VIEW A
PIN 1
52
14
1
0.23
0.11
13
0.65 BSC
0.38
0.22
2.10
2.00
1.95
7
0
0.10 MIN
COPLANARITY
VIEW A
ROTATED 90 CCW
COMPLIANT TO JEDEC STANDARDS MO-022-AC-1
56-Lead Lead Frame Chip Scale Package [LFCSP]
8  8 mm Body
(CP-56)
Dimensions shown in millimeters
8.00
BSC SQ
0.60 MAX
0.60 MAX
42
PIN 1
INDICATOR
7.75
BSC SQ
TOP
VIEW
0.20
REF
12 MAX
PIN 1
INDICATOR
56 1
6.25
6.10 SQ
5.95
BOTTOM
VIEW
0.50
0.40
0.30
1.00
0.90
0.80
43
0.30
0.23
0.18
29
28
15 14
6.50
REF
0.70 MAX
0.65 NOM
0.05 MAX
0.02 NOM
0.50 BSC
SEATING
PLANE
COPLANARITY
0.08
COMPLIANT TO JEDEC STANDARDS MO-220-VLLD-2
Revision History
Location
Page
4/03—Data Sheet changed from REV. 0 to REV. A.
Updated OUTLINE DIMENSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
–80–
REV. A