19-2885; Rev 0; 6/03
MAX1231 Evaluation Kit/
MAX1231 Evaluation System
This system can also evaluate the MAX1030, MAX1031,
and MAX1230. Contact the factory for free samples of
these products. See the Detailed Description of
Hardware section.
MAX1231 Stand-Alone EV Kit
The MAX1231 EV kit provides a proven PC board layout
to facilitate evaluation of the MAX1231. It must be interfaced to appropriate timing signals for proper operation. Connect 3V and ground return to terminal block
TB1 (Figure 5). Refer to the MAX1227/MAX1229/
MAX1231 data sheet for timing requirements.
MAX1231 EV System
The MAX1231 EV system operates from a user-supplied 7VDC to 20VDC power supply. The evaluation
software runs under Windows 95/98/2000 on an IBM
PC, interfacing to the EV system board through the
computer’s serial communications port. See the Quick
Start section for setup and operating instructions.
Features
♦ Proven PC Board Layout
♦ Complete Evaluation System
♦ Convenient On-Board Test Points
♦ Data-Logging Software
♦ Fully Assembled and Tested
Ordering Information
PART
TEMP RANGE
INTERFACE TYPE
MAX1231EVKIT
0°C to +70°C
User supplied
MAX1231EVC16
0°C to +70°C
Windows software
Note: The MAX1231 evaluation software is designed for use
with the complete evaluation system MAX1231EVC16 (includes
the 68HC16MODULE-DIP module together with the
MAX1231EVKIT). If the MAX1231 evaluation software is not to
be used, the MAX1231EVKIT can be purchased by itself, without the µC.
MAX1231EVC16 Component List
PART
QTY
DESCRIPTION
MAX1231EVKIT
1
MAX1231 evaluation kit
68HC16MODULE-DIP
1
68HC16 µC module
Component Suppliers
SUPPLIER
PHONE
FAX
WEBSITE
TDK
847-803-6100
847-390-4405
www.component.tdk.com
Note: Please indicate you are using the MAX1231 when contacting these component suppliers.
Windows is a registered trademark of Microsoft Corp.
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
1
Evaluates: MAX1030/MAX1031/MAX1230/MAX1231
General Description
The MAX1231 evaluation system (EV system) consists of
a MAX1231 evaluation kit (EV kit) and a Maxim
68HC16MODULE-DIP microcontroller (µC) module. The
MAX1231 is a 12-bit, 300ksps analog-to-digital converter
(ADC) with an internal temperature sensor, first-in/firstout (FIFO), and an internal reference. The evaluation
software runs under Windows® 95/98/2000, providing a
handy user interface to exercise the MAX1231 features.
Order the complete EV system (MAX1231EVC16) for
comprehensive evaluation of the MAX1231 using a personal computer. Order the EV kit (MAX1231EVKIT) if
the 68HC16MODULE module has already been purchased with a Maxim EV system, or for custom use in
other µC-based systems.
Evaluates: MAX1030/MAX1031/MAX1230/MAX1231
MAX1231 Evaluation Kit/
MAX1231 Evaluation System
MAX1231EVKIT Component List
DESIGNATION QTY
DESCRIPTION
C1–C16
16
0.01µF ±10% ceramic capacitors
(1206)
C17
1
0.1µF ceramic capacitor (1206)
C18
1
10µF ±20%, 6.3V X5R ceramic
capacitor (0805)
TDK C2012X5R0J106M
H1
1
7-pin header
J1
1
2 x 20 right-angle socket
JU1 2-3
1
Shunt
JU1
1
3-pin header
JU2
0
Shorted trace on PC board
R1–R16
16
10Ω ±5% resistors (1206)
TB1
1
2-circuit terminal block, 5.08mm pitch
TB2–TB5
4
5-circuit terminal blocks, 5.08mm
pitch
U1
1
MAX1231BCEG-T (24-pin QSOP)
U2
1
MAX1615EUK-T, ABZD, (5-pin SOT23)
U3, U4
2
MAX1840EUB (10-pin µMAX)
or MAX1841EUB
None
1
MAX1231 evaluation kit PC board
Quick Start
Required Equipment
Before you begin, you need the following equipment:
• MAX1231EVC16 (contains the MAX1231EVKIT and
the 68HC16MODULE-DIP)
• DC power supply, +7VDC to +20VDC at 0.25A
• Windows 95/98/2000 computer with a spare serial
(COM) port
• 9-pin I/O extension cable
Procedure
Do not turn on the power until all connections are
made:
1) Ensure that JU1 is in the 2-3 position (Table 2).
2) Carefully connect the boards by aligning the 40-pin
header of the MAX1231 EV kit with the 40-pin connector of the 68HC16MODULE-DIP module. Gently
press them together. The two boards should be
flush against one another.
3) Connect a +7VDC to +20VDC power source to the
µC module at the terminal block located next to the
on/off switch, along the top edge of the µC module.
Observe the polarity marked on the board.
4) Connect a cable from the computer’s serial port to
the µC module. If using a 9-pin serial port, use a
straight-through, 9-pin female-to-male cable. If the
only available serial port uses a 25-pin connector, a
standard 25-pin to 9-pin adapter is required. The
EV kit software checks the modem status lines
(CTS, DSR, DCD) to confirm that the correct port
has been selected.
5) Install the evaluation software on your computer by
running the INSTALL.EXE program on the floppy
disk. The program files are copied and icons are
created for them in the Windows start menu.
6) Turn on the power supply.
7) Start the MAX1231 program by opening its icon in
the start menu.
8) The program prompts you to connect the µC module and turn its power on. Slide SW1 to the ON position. Select the correct serial port, and click OK.
The program automatically downloads its software
to the module.
9) Apply an input signal to AIN0 and click Perform
Action. Observe the readout on the screen. To perform the action repeatedly, check the every 200ms
box.
10) To view a graph of the measurements, pull down
the View menu and click Graph.
Detailed Software Description
The evaluation software’s main window configures the
data converter and measures the analog inputs. Under
Action, select a scanning sequence, repetitive conversions, or a single conversion. Each selected channel’s
measurement results are displayed in the corresponding Measurement Results field.
The Action setting read single channel repeatedly
requires making a selection under Repetition to determine how many times the selected channel should be
measured.
Use Averaging to summarize a series of measurement
results on each selected channel as an arithmetic
mean value. Repetition can be used together with
Averaging to summarize a large number of measurement results as a small number of sample means.
Note: Bold items are software settings or commands.
2
_______________________________________________________________________________________
MAX1231 Evaluation Kit/
MAX1231 Evaluation System
The Setup tab configures the alternate functions for the
AIN14 and AIN15 pins, and also configures adjacent
channels as differential input pairs.
The Low-level registers tab summarizes the commands
that create the active configuration. The Reset All
Registers button resets these software-shadowed register values and sends the reset command to the MAX1231.
Table 1. Graph Tool Buttons
TOOL
FUNCTION
Show the entire available input range.
TOOL
FUNCTION
Show standard deviation in tabular view:
Expand the graph data to fill the window.
Move the view left or right.
S tandard deviation =
Move the view up or down.
Expand or contract the x-axis.
Expand or contract the y-axis.
Load data from a file.
Save data to a file.
( )
n∑ × - ∑ ×
n
n
(n -1)n
2
2
Show root of the mean of the squares (RMS) in
tabular view:
∑ ×2
RMS =
( )
n
Channel 0 enable
Option to write a header line when saving data.
Option to write line numbers when saving data.
View code vs. time plot.
Channel 1 enable
Channel 2 enable
Channel 3 enable
View histogram plot (cumulative frequency of
each code).
Channel 4 enable
View table.
Channel 5 enable
Show minimum in tabular view.
Channel 6 enable
Show maximum in tabular view.
Channel 7 enable
Show span in tabular view.
Span = maximum - minimum
Channel 8 enable
Show number of samples in tabular view.
Show sum of the samples in tabular view.
Show sum of the squares of the samples in
tabular view.
Channel 9 enable
Channel 10 enable
Channel 11 enable
Channel 12 enable
Channel 13 enable
Show arithmetic mean in tabular view:
Mean =
∑( × )
Channel 14 enable
n
_______________________________________________________________________________________
3
Evaluates: MAX1030/MAX1031/MAX1230/MAX1231
The Low-Level Interface Details panel shows the most
recent low-level register write. A summary of what has
been written to each register is available under the
Low-level registers tab.
The AIN14 and AIN15 channels are automatically
skipped if their alternate functions are selected in the
setup register. The evaluation software updates its display to show or hide these channels whenever the
alternate functions are enabled or disabled.
Evaluates: MAX1030/MAX1031/MAX1230/MAX1231
MAX1231 Evaluation Kit/
MAX1231 Evaluation System
Sampling
Measurement data can be sampled in external clock
mode. From the Setup tab, set Clock Mode to
0111xxxx ext clock. Then, return to the Measurement
tab and click Get Samples.
Graph Window
To view recently measured data, drop down the View
menu and choose Graph. Data can be viewed as a time
sequence plot, a histogram plot, or as a table of raw
numbers. See Table 1 for available graph commands.
four times the actual measurement code number.
Reconstructed voltage values are unaffected. Adjust
the graph window by selecting its Options menu; set
its Sub-LSBs to 2.
Evaluating the MAX1230
The MAX1230 is the 5V version of the MAX1231. To
evaluate the MAX1230, request a free sample of the
MAX1230BCEG. Replace U1 with a MAX1230, and
move the shunt to the 5V position. In the software’s
Options menu, select Reference = 4.096V.
Diagnostics Window
Using an External Reference
The diagnostics window is used for factory testing prior
to shipping the evaluation kit. It is not meant for customer use.
An external reference can be applied in single-ended or
differential mode. In differential mode, analog input pin
AIN14 is used as the REF(-) return connection. In singleended mode, the reference returns to common ground.
With the power off, connect the external reference. Then
power up the system and run the evaluation software.
Under Setup, select the appropriate reference input configuration. If using a single-ended reference, set
Reference Input to 01xx01xx pin15 = AIN14. If using a
differential reference, set Reference Input to 01xx11xx
pin 15 = REF-.
Detailed Hardware Description
The MAX1231 device under test (U1) is a 12-bit,
300ksps ADC with an internal temperature sensor,
FIFO, and an internal reference. Resistors R1–R16 and
capacitors C1–C16 form single-pole, lowpass, antialiasing filters for each input. Capacitor C17 provides
power-supply bypassing for U1 (Figure 5). Refer to the
MAX1227/MAX1229/MAX1231 data sheet.
The EV kit includes a MAX1615 3V/5V linear regulator
(U2) and a set of MAX1840/MAX1841 level shifters (U3
and U4) to support using the 3V MAX1230 with the 5V µC.
Evaluating the MAX1030
The MAX1030 is the 5V, 10-bit version of the MAX1231.
To evaluate the MAX1030, request a free sample of
MAX1030BCEG. Replace U1 with a MAX1030, and
move JU1 shunt to the 5V position. In the software’s
Options menu, select Reference = 4.096V.
The evaluation software expects 12 bits of data, but the
MAX1030 only provides 10 bits of meaningful data.
Because the most significant bits are aligned, the measurement code numbers reported by the software are
four times the actual measurement code number.
Reconstructed voltage values are unaffected. Adjust
the graph window by selecting its Options menu; set
its Sub-LSBs to 2.
Evaluating the MAX1031
The MAX1031 is the 10-bit version of the MAX1231. To
evaluate the MAX1031, request a free sample of the
MAX1031BCEG. Replace U1 with a MAX1031, and
move the JU1 shunt to the 3V position.
The evaluation software expects 12 bits of data, but the
MAX1031 only provides 10 bits of meaningful data.
Because the most significant bits are aligned, the measurement code numbers reported by the software are
4
Table 2. Jumper JU1 (VDD Voltage
Selection)
SHUNT
POSITION
VDD (V)
1–2
5V
Normal operation with U1 =
MAX1230 or MAX1030.
2–3*
3V
Normal operation with U1 =
MAX1231 or MAX1031.
Open
Unspecified
FUNCTION
Do not operate kit with JU1 open.
*Indicates default configuration.
Table 3. Optional Jumper JU2 (AIN15
Alternate Function)
JU2 STATE
U1 PIN 16
CONNECTION
Connected to µC
Closed*
module J1 pin 29
(default trace
(through level
on PC board)
shifter)
Open
Connected to TB5
pin 4
FUNCTION
U1 pin 16 = CNVST
conversion start
command. Leave TB5
pin 4 unconnected.
U1 pin 16 = AIN15
analog input. Connect
signal source to terminal
block TB5 pin 4.
*Indicates default configuration.
_______________________________________________________________________________________
MAX1231 Evaluation Kit/
MAX1231 Evaluation System
Problem: Unacceptable errors occur when measuring
a transducer.
Solution: Although most signal sources can be connected directly to the MAX1231’s analog inputs, some
high-impedance signal sources can require an input
buffer. Check for settling errors by increasing the
acquisition time (internal clock mode 01). If necessary,
use a MAX4430 to buffer high-impedance signal
sources.
Figure 1. The MAX1231 evaluation software’s main window configures the data converter and measures the analog inputs.
_______________________________________________________________________________________
5
Evaluates: MAX1030/MAX1031/MAX1230/MAX1231
Troubleshooting
Problem: No output measurement. System seems to
report zero voltage or fails to make a measurement.
Solution: Check VDD supply voltage. Check the reference voltage using a digital voltmeter. Use an oscilloscope to verify that the conversion-start signal is being
strobed.
Problem: Measurements are erratic, unstable, or have
poor accuracy.
Solution: Check the reference voltage using a digital
voltmeter. Use an oscilloscope to check for noise.
When probing for noise, keep the oscilloscope ground
return lead as short as possible, preferably less than
0.5in (10mm).
Evaluates: MAX1030/MAX1031/MAX1230/MAX1231
MAX1231 Evaluation Kit/
MAX1231 Evaluation System
Figure 2. The main window’s Setup tab configures the alternate functions for AIN14 and AIN15, and also configures adjacent channels as differential input pairs.
6
_______________________________________________________________________________________
MAX1231 Evaluation Kit/
MAX1231 Evaluation System
Evaluates: MAX1030/MAX1031/MAX1230/MAX1231
Figure 3. The main window’s Low-level registers tab summarizes the commands that create the active configuration.
_______________________________________________________________________________________
7
Evaluates: MAX1030/MAX1031/MAX1230/MAX1231
MAX1231 Evaluation Kit/
MAX1231 Evaluation System
Figure 4. The real-time data and sampled data graphs display data as a time sequence, histogram, or table.
8
_______________________________________________________________________________________
MAX1231 Evaluation Kit/
MAX1231 Evaluation System
Evaluates: MAX1030/MAX1031/MAX1230/MAX1231
H1
TERMINAL BLOCK
HEADER
R1
10Ω
1
TB2–1
R2
10Ω
R3
10Ω
R4
10Ω
TERMINAL BLOCK
R7
10Ω
R8
10Ω
TERMINAL BLOCK
TB4–1
R10
10Ω
TB4
R12
10Ω
AIN3
MAX1231
CS
21
AIN4
SCLK
H1–4
20
H1–5
SCLK
VDD
6
AIN5
VDD
19
C6
0.01µF
H1–6
C17
0.1µF
7
AIN6
GND
VDD
18
H1–7
C7
0.01µF
GND
8
AIN7
REF+
REF+
17
TB5
C8
0.01µF
9
AIN8
CNVST/AIN15
10
AIN9
REF-/AIN14
15
11
AIN10
AIN13
14
C12
0.01µF
AIN11
AIN12
R14
10Ω
TB5–2
C14
0.01µF
12
R15
10Ω
TB5–3
C15
0.01µF
C11
0.01µF
TERMINAL BLOCK
TB5–4
C16
0.01µF
C10
0.01µF
TB4–4
R16
CNVST 10Ω
16
C9
0.01µF
TB4–3
TB4–5
H1–3
DIN
CS
5
TB4–2
R11
10Ω
22
C5
0.01µF
TB3–4
R9
10Ω
DIN
AIN2
U1
4
TB3–3
TB3–5
H1–2
C4
0.01µF
TB3–2
TB3
23
DOUT
3
TB3–1
R6
10Ω
DOUT
AIN1
C3
0.01µF
TB2–4
R5
10Ω
H1–1
C2
0.01µF
TB2–3
TB2–5
24
EOC
2
TB2–2
TB2
EOC
AIN0
C1
0.01µF
13
R13
10Ω
TB5–1
C13
0.01µF
TB5–5
Figure 5a. MAX1231 EV Kit Schematic (Sheet 1 of 2)
_______________________________________________________________________________________
9
Evaluates: MAX1030/MAX1031/MAX1230/MAX1231
MAX1231 Evaluation Kit/
MAX1231 Evaluation System
+12V
J1
TB1
CONNECTOR
TERMINAL BLOCK
J1–9
J1–10
J1–11
J1–12
J1–13
J1–14
J1–15
J1–16
J1–17
J1–18
J1–19
J1–20
J1–21
J1–22
J1–23
J1–24
J1–25
J1–26
J1–28
J1–30
J1–32
J1–33
N.C.
N.C.
N.C.
N.C.
N.C.
N.C.
1
J1–5
J1–6
2
J1–1
N.C.
N.C.
N.C.
GND
J1–2
TB1–1
3
C18
10µF
6.3V
J1–38
+5V
J1–7
1
2
J1–8
3
J1–37
4
J1–36
N.C.
+5V
5
VDD
5/3 4
(FB)
OUT
DATA
TB1–2
MAX1615
VDD
J1–3
J1–4
N.C.
N.C.
5
U1
N.C.
N.C.
SHDN
IN
U3
I/O
DVCC
VCC
CIN
CLK
MAX1840
RIN
RST
SHDN
GND
JU1
10
1
2
3
CS
9
VDD
8
SCLK
7
DIN
6
N.C.
N.C.
N.C.
N.C.
N.C.
N.C.
N.C.
N.C.
6
J1–31
J1–35
J1–40
J1–39
J1–34
J1–27
J1–29
7
N.C.
8
N.C.
N.C.
N.C.
N.C.
+5V
9
10
SHDN
GND
U4
RST
RIN
CLK
CIN
MAX1840
VCC
DVCC
I/O
DATA
5
VDD
4
EOC
3
DOUT
2
VDD
1
CNVST
JU2
Figure 5b. MAX1231 EV Kit Schematic (Sheet 2 of 2)
10
______________________________________________________________________________________
MAX1231 Evaluation Kit/
MAX1231 Evaluation System
Evaluates: MAX1030/MAX1031/MAX1230/MAX1231
Figure 6. MAX1231 EV Kit Component Placement Guide—Component Side
Figure 7. MAX1231 EV Kit PC Board Layout—Component Side
______________________________________________________________________________________
11
Evaluates: MAX1030/MAX1031/MAX1230/MAX1231
MAX1231 Evaluation Kit/
MAX1231 Evaluation System
Figure 8. MAX1231 EV Kit PC Board Layout—Solder Side
12
______________________________________________________________________________________
MAX1231 Evaluation Kit/
MAX1231 Evaluation System
Evaluates: MAX1030/MAX1031/MAX1230/MAX1231
// Drv1231.h
// MAX1231-specific driver.
// (C) 2003 Maxim Integrated Products
//--------------------------------------------------------------------------#ifndef DRV1231H
#define DRV1231H
//--------------------------------------------------------------------------//-------------------------------------------------// MAX1231 Conversion register
// 1 x x x x x x x
#define MAX1231_CONV
0x80
//
// Power-on state: 1000 0000
#define MAX1231_CONV_POR
0x80
//
// Channel Selection
#define MAX1231_CONV_AIN00
0x80
#define MAX1231_CONV_AIN01
0x88
#define MAX1231_CONV_AIN02
0x90
#define MAX1231_CONV_AIN03
0x98
#define MAX1231_CONV_AIN04
0xA0
#define MAX1231_CONV_AIN05
0xA8
#define MAX1231_CONV_AIN06
0xB0
#define MAX1231_CONV_AIN07
0xB8
#define MAX1231_CONV_AIN08
0xC0
#define MAX1231_CONV_AIN09
0xC8
#define MAX1231_CONV_AIN10
0xD0
#define MAX1231_CONV_AIN11
0xD8
#define MAX1231_CONV_AIN12
0xE0
#define MAX1231_CONV_AIN13
0xE8
#define MAX1231_CONV_AIN14
0xF0
#define MAX1231_CONV_AIN15
0xF8
//
// Actions
#define MAX1231_CONV_SCAN_00_N
#define MAX1231_CONV_SCAN_T_00_N
#define MAX1231_CONV_SCAN_N_15
#define MAX1231_CONV_SCAN_T_N_15
#define MAX1231_CONV_SINGLE_REPEAT
#define MAX1231_CONV_SINGLE_READ
//
#define MAX1231_ACTION_MASK
/*
/*
/*
/*
/*
/*
/*
/*
/*
/*
/*
/*
/*
/*
/*
/*
10000xxx
10001xxx
10010xxx
10011xxx
10100xxx
10101xxx
10110xxx
10111xxx
11000xxx
11001xxx
11010xxx
11011xxx
11100xxx
11101xxx
11110xxx
11111xxx
AIN0 */
AIN1 */
AIN2 */
AIN3 */
AIN4 */
AIN5 */
AIN6 */
AIN7 */
AIN8 */
AIN9 */
AIN10 */
AIN11 */
AIN12 */
AIN13 */
AIN14 */
AIN15 */
0x80
0x81
0x82
0x83
0x84
0x86
/*
/*
/*
/*
/*
/*
1xxxx000
1xxxx001
1xxxx010
1xxxx011
1xxxx10x
1xxxx11x
Scan
Scan
Scan
Scan
Read
Read
0,1,2,...N */
T,0,1,2,..N */
N,N+1,...,15 */
T,N,N+1,...,15 */
repeatedly */
once */
0x87
/* 1xxxx111 bits to test*/
//-------------------------------------------------// MAX1231 Setup register
// 0 1 x x x x 0 0
//
// Setup register may optionally be followed by
// one of the the differential configuration registers.
// 01xxxx10 followed by a second byte, selecting Unipolar-Differential inputs
// 01xxxx11 followed by a second byte, selecting Bipolar-Differential inputs
#define MAX1231_SETUP
0x40
/* 01xxxx00 no additional bytes */
#define MAX1231_SETUP_UNIDIFF
0x42
/* 01xxxx10 followed by another byte */
#define MAX1231_SETUP_BIPDIFF
0x43
/* 01xxxx11 followed by another byte */
//
// Power-on state: 0110 0000
#define MAX1231_SETUP_POR
0x60
//
// Clock Mode
// 0100xxxx pin16=CNVST, Int clock, Triggered by CNVST pulse
// 0101xxxx pin16=CNVST, Int clock, Triggered by CNVST pulses, custom Tacq
// 0110xxxx pin16=AIN15, Int clock, Triggered by conversion register write
// 0111xxxx pin16=AIN15, Ext clock, Triggered by conversion register write
#define MAX1231_SETUP_INTCLK_CNVST
0x40
/* 0100xxxx CNVST */
Listing 1 (Sheet 1 of 4)
______________________________________________________________________________________
13
Evaluates: MAX1030/MAX1031/MAX1230/MAX1231
MAX1231 Evaluation Kit/
MAX1231 Evaluation System
#define MAX1231_SETUP_INTCLK_CNVST_TACQ
0x50
#define MAX1231_SETUP_INTCLK
0x60
#define MAX1231_SETUP_EXTCLK
0x70
//
// Reference Voltage
// 01xx00xx pin15=AIN14, Internal reference, need wake-up delay
// 01xx01xx pin15=AIN14, External reference, single-ended
// 01xx10xx pin15=AIN14, Internal reference, always on
// 01xx11xx pin15=REF-, External reference, differential
#define MAX1231_SETUP_INTREF_SLEEP
0x40
/*
#define MAX1231_SETUP_EXTREF
0x44
/*
#define MAX1231_SETUP_INTREF_ACTIVE
0x48
/*
#define MAX1231_SETUP_EXTREF_DIFF
0x4C
/*
//
// MAX1231 Unipolar-Differential input pairs
// Byte Following MAX1231_SETUP_UNIDIFF
// 0 1 x x x x 1 0 unidiff
//
// Power-on state: 0110 0010 0000 0000
#define MAX1231_SETUP_UNIDIF_POR
0x00
//
#define MAX1231_SETUP_UNIDIF0001
0x80
#define MAX1231_SETUP_UNIDIF0203
0x40
#define MAX1231_SETUP_UNIDIF0405
0x20
#define MAX1231_SETUP_UNIDIF0607
0x10
#define MAX1231_SETUP_UNIDIF0809
0x08
#define MAX1231_SETUP_UNIDIF1011
0x04
#define MAX1231_SETUP_UNIDIF1213
0x02
#define MAX1231_SETUP_UNIDIF1415
0x01
//
// MAX1231 Bipolar-Differential input pairs
// Byte Following MAX1231_SETUP_BIPDIFF
// 0 1 x x x x 1 1 bipdiff
//
// Power-on state: 0110 0011 0000 0000
#define MAX1231_SETUP_BIPDIF_POR
0x00
//
#define MAX1231_SETUP_BIPDIF0001
0x80
#define MAX1231_SETUP_BIPDIF0203
0x40
#define MAX1231_SETUP_BIPDIF0405
0x20
#define MAX1231_SETUP_BIPDIF0607
0x10
#define MAX1231_SETUP_BIPDIF0809
0x08
#define MAX1231_SETUP_BIPDIF1011
0x04
#define MAX1231_SETUP_BIPDIF1213
0x02
#define MAX1231_SETUP_BIPDIF1415
0x01
//-------------------------------------------------// MAX1231 Averaging register
// 0 0 1 x x x x x
//
// Power-on state: 0010 0000
#define MAX1231_AVERAGE_POR
0x20
//
// Averaging
// 001000xx One measurement result (no averaging)
// 001100xx Mean of 4 measurement results
// 001101xx Mean of 8 measurement results
// 001110xx Mean of 16 measurement results
// 001111xx Mean of 32 measurement results
#define MAX1231_AVERAGE_1
0x20
#define MAX1231_AVERAGE_4
0x30
#define MAX1231_AVERAGE_8
0x34
#define MAX1231_AVERAGE_16
0x38
#define MAX1231_AVERAGE_32
0x3C
/*
/*
/*
/*
/*
001000xx
001100xx
001101xx
001110xx
001111xx
/* 0101xxxx CNVST */
/* 0110xxxx AIN15 */
/* 0111xxxx AIN15 */
01xx00xx
01xx01xx
01xx10xx
01xx11xx
AIN14 */
AIN14 */
AIN14 */
REF(-) */
No averaging */
Mean of 4 measurements */
Mean of 8 measurements */
Mean of 16 measurements */
Mean of 32 measurements */
Listing 1 (Sheet 2 of 4)
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MAX1231 Evaluation System
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//
// Repeat Count
// Enabled by MAX1231_CONV_SINGLE_REPEAT 1xxxx10x
// Internal clock modes only
#define MAX1231_REPEAT_4
0x20
/* 001xxx00
#define MAX1231_REPEAT_8
0x21
/* 001xxx01
#define MAX1231_REPEAT_12
0x22
/* 001xxx10
#define MAX1231_REPEAT_16
0x23
/* 001xxx11
4 times */
8 times */
12 times */
16 times */
//-------------------------------------------------// MAX1231 Reset register (reset command)
// 0 0 0 1 x x x x
//
// Reset only the FIFO entries
#define MAX1231_RESET_FIFO
0x18
/* 00011xxx Reset FIFO data registers */
//
// Reset all registers to their power-on default states
#define MAX1231_RESET_ALL
0x10
/* 00010xxx Reset All Registers */
//-------------------------------------------------// Enumerated type defining the meaning of each of the
// MAX1231's FIFO data slots.
typedef enum {
//
// Unused FIFO slot; meaningless data.
UNDEFINED = 0,
//
// Temperature measurement.
// The scan modes always place temperature data
// at the head of the FIFO.
TEMPERATURE,
//
// Single-ended unipolar analog inputs.
// Code 0x0000 = minimum voltage
// Code 0x0FFF = maximum voltage
// Note that AIN14 and AIN15 pins have optional alternate functions.
UNIAIN00, UNIAIN01, UNIAIN02, UNIAIN03,
UNIAIN04, UNIAIN05, UNIAIN06, UNIAIN07,
UNIAIN08, UNIAIN09, UNIAIN10, UNIAIN11,
UNIAIN12, UNIAIN13, UNIAIN14, UNIAIN15,
//
// Unipolar differential input pairs.
// Code 0x0000 = minimum voltage
// Code 0x0FFF = maximum voltage
UNIDIF0001, UNIDIF0203, UNIDIF0405, UNIDIF0607,
UNIDIF0809, UNIDIF1011, UNIDIF1213, UNIDIF1415,
//
// Bipolar differential input pairs.
// Code 0x07FF = maximum voltage
// Code 0x0000 = zero volts
// Code 0x0800 = minimum voltage
BIPDIF0001, BIPDIF0203, BIPDIF0405, BIPDIF0607,
BIPDIF0809, BIPDIF1011, BIPDIF1213, BIPDIF1415,
//
NUM_FIFO_ENTRY_TYPES
} MAX1231_fifo_entry_t;
//-------------------------------------------------// Enumerated type defining each pair of MAX1231 inputs
// as single-ended or differential
typedef enum {
SINGLE_ENDED = 0,
UNIPOLAR_DIFFERENTIAL,
Listing 1 (Sheet 3 of 4)
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MAX1231 Evaluation System
BIPOLAR_DIFFERENTIAL
} MAX1231_channel_config_t;
//-------------------------------------------------// C++ class representing the state of a MAX1231
class MAX1231
{
public:
// MAX1231 registers cannot be read,
// so keep track of the register values here.
int conversion_register;
int new_conversion_register;
int setup_register;
int setup_unidiff_register;
int setup_bipdiff_register;
int averaging_register;
// The reference voltage is used to calculate the input voltage
// represented by each measurement.
double Vref;
// Constructor for class MAX1231.
MAX1231(void);
// Input configuration
// Array InputPairConfig[] determines whether each pair
// of input channels is configured as two single-ended inputs,
// a unipolar differential pair, or a bipolar differential pair.
MAX1231_channel_config_t InputPairConfig[8];
//
// Member function to figure out the values of InputPairConfig
// based on the MAX1231 register values.
// Call this function afer setting setup_unidiff_register and setup_bipdiff_register
// before using the values of InputPairConfig[].
void Update_InputPairConfig(void);
// The MAX1231 has a FIFO data buffer with
// 16 entries (plus an optional temperature measurement).
// Array FIFO_meaning[] determines what to do with
// each successive word read from the MAX1231.
MAX1231_fifo_entry_t FIFO_meaning[17];
//
// Member function to figure out the values of FIFO_meaning
// based on the MAX1231 register values.
// Call this function afer setting conversion_register, setup_register, and averaging_register
// before using the values of FIFO_meaning[].
void Update_FIFO_meaning(void);
int channel (MAX1231_fifo_entry_t meaning) {
if ((UNIAIN00 <= meaning) && (meaning <= UNIAIN15)) {
return (meaning - UNIAIN00);
} else
if ((UNIDIF0001 <= meaning) && (meaning <= UNIDIF1415)) {
return (meaning - UNIDIF0001) * 2;
} else
if ((BIPDIF0001 <= meaning) && (meaning <= BIPDIF1415)) {
return (meaning - BIPDIF0001) * 2;
} else
if (meaning == TEMPERATURE) {
return 16;
} else {
return 0;
}
};};
//--------------------------------------------------------------------------#endif // DRV1231H
Listing 1 (Sheet 4 of 4)
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// Drv1231.cpp
// MAX1231-specific driver.
// (C) 2003 Maxim Integrated Products
//--------------------------------------------------------------------------#include "Drv1231.h"
//--------------------------------------------------------------------------MAX1231::MAX1231(void)
{
conversion_register = MAX1231_CONV_POR;
setup_register = MAX1231_SETUP_POR;
setup_unidiff_register = MAX1231_SETUP_UNIDIF_POR;
setup_bipdiff_register = MAX1231_SETUP_BIPDIF_POR;
averaging_register = MAX1231_AVERAGE_POR;
Vref = 2.500;
for (int index = 0; index < 8; index++) {
InputPairConfig[index] = SINGLE_ENDED;
}
for (int index = 0; index < 17; index++) {
FIFO_meaning[index] = UNDEFINED;
}
}
//--------------------------------------------------------------------------void MAX1231::Update_InputPairConfig(void)
{
for (int index = 0; index < 8; index++) {
InputPairConfig[index] = SINGLE_ENDED;
}
if (setup_bipdiff_register & MAX1231_SETUP_BIPDIF0001)
InputPairConfig[0] = BIPOLAR_DIFFERENTIAL;
if (setup_bipdiff_register & MAX1231_SETUP_BIPDIF0203)
InputPairConfig[1] = BIPOLAR_DIFFERENTIAL;
if (setup_bipdiff_register & MAX1231_SETUP_BIPDIF0405)
InputPairConfig[2] = BIPOLAR_DIFFERENTIAL;
if (setup_bipdiff_register & MAX1231_SETUP_BIPDIF0607)
InputPairConfig[3] = BIPOLAR_DIFFERENTIAL;
if (setup_bipdiff_register & MAX1231_SETUP_BIPDIF0809)
InputPairConfig[4] = BIPOLAR_DIFFERENTIAL;
if (setup_bipdiff_register & MAX1231_SETUP_BIPDIF1011)
InputPairConfig[5] = BIPOLAR_DIFFERENTIAL;
if (setup_bipdiff_register & MAX1231_SETUP_BIPDIF1213)
InputPairConfig[6] = BIPOLAR_DIFFERENTIAL;
if (setup_bipdiff_register & MAX1231_SETUP_BIPDIF1415)
InputPairConfig[7] = BIPOLAR_DIFFERENTIAL;
if (setup_unidiff_register & MAX1231_SETUP_UNIDIF0001)
InputPairConfig[0] = UNIPOLAR_DIFFERENTIAL;
if (setup_unidiff_register & MAX1231_SETUP_UNIDIF0203)
InputPairConfig[1] = UNIPOLAR_DIFFERENTIAL;
if (setup_unidiff_register & MAX1231_SETUP_UNIDIF0405)
InputPairConfig[2] = UNIPOLAR_DIFFERENTIAL;
if (setup_unidiff_register & MAX1231_SETUP_UNIDIF0607)
InputPairConfig[3] = UNIPOLAR_DIFFERENTIAL;
if (setup_unidiff_register & MAX1231_SETUP_UNIDIF0809)
InputPairConfig[4] = UNIPOLAR_DIFFERENTIAL;
if (setup_unidiff_register & MAX1231_SETUP_UNIDIF1011)
InputPairConfig[5] = UNIPOLAR_DIFFERENTIAL;
if (setup_unidiff_register & MAX1231_SETUP_UNIDIF1213)
InputPairConfig[6] = UNIPOLAR_DIFFERENTIAL;
if (setup_unidiff_register & MAX1231_SETUP_UNIDIF1415)
InputPairConfig[7] = UNIPOLAR_DIFFERENTIAL;
}
//--------------------------------------------------------------------------void MAX1231::Update_FIFO_meaning(void)
{
int conversion_register = new_conversion_register;
Listing 2 (Sheet 1 of 4)
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for (int index = 0; index < 17; index++) {
FIFO_meaning[index] = UNDEFINED;
}
int channel_field = (conversion_register >> 3) & 0x0F;
int channel_index = channel_field;
int repeat_count = 4;
switch(averaging_register & 0xE3) {
case MAX1231_REPEAT_4: // 001xxx00 4 times
repeat_count = 4;
break;
case MAX1231_REPEAT_8: // 001xxx01 8 times
repeat_count = 8;
break;
case MAX1231_REPEAT_12: // 001xxx10 12 times
repeat_count = 12;
break;
case MAX1231_REPEAT_16: // 001xxx11 16 times
repeat_count = 16;
break;
}
MAX1231_fifo_entry_t meaning =
(MAX1231_fifo_entry_t)(UNIAIN00 + channel_field);
if (InputPairConfig[channel_field / 2] == BIPOLAR_DIFFERENTIAL) {
meaning = (MAX1231_fifo_entry_t)(BIPDIF0001 + channel_field/2);
} else if (InputPairConfig[channel_field / 2] == UNIPOLAR_DIFFERENTIAL) {
meaning = (MAX1231_fifo_entry_t)(UNIDIF0001 + channel_field/2);
}
int index = 0;
switch(conversion_register & MAX1231_ACTION_MASK) {
case MAX1231_CONV_SCAN_00_N:
meaning = UNIAIN00;
channel_index = 0;
while(channel_index <= channel_field) {
int pair_index = channel_index / 2;
if (InputPairConfig[pair_index] == BIPOLAR_DIFFERENTIAL) {
meaning = (MAX1231_fifo_entry_t)(BIPDIF0001 + pair_index);
FIFO_meaning[index++] = meaning;
channel_index = channel_index + 2;
} else if (InputPairConfig[pair_index] == UNIPOLAR_DIFFERENTIAL) {
meaning = (MAX1231_fifo_entry_t)(UNIDIF0001 + pair_index);
FIFO_meaning[index++] = meaning;
channel_index = channel_index + 2;
} else {
meaning = (MAX1231_fifo_entry_t)(UNIAIN00 + channel_index);
FIFO_meaning[index++] = meaning;
channel_index = channel_index + 1;
}
}
break;
case MAX1231_CONV_SCAN_T_00_N:
FIFO_meaning[index++] = TEMPERATURE;
meaning = UNIAIN00;
channel_index = 0;
while(channel_index <= channel_field) {
int pair_index = channel_index / 2;
if (InputPairConfig[pair_index] == BIPOLAR_DIFFERENTIAL) {
meaning = (MAX1231_fifo_entry_t)(BIPDIF0001 + pair_index);
FIFO_meaning[index++] = meaning;
channel_index = channel_index + 2;
} else if (InputPairConfig[pair_index] == UNIPOLAR_DIFFERENTIAL) {
meaning = (MAX1231_fifo_entry_t)(UNIDIF0001 + pair_index);
FIFO_meaning[index++] = meaning;
channel_index = channel_index + 2;
} else {
meaning = (MAX1231_fifo_entry_t)(UNIAIN00 + channel_index);
FIFO_meaning[index++] = meaning;
channel_index = channel_index + 1;
}
}
Listing 2 (Sheet 2 of 4)
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break;
case MAX1231_CONV_SCAN_N_15:
while (index < 17) {
int pair_index = channel_index / 2;
if (InputPairConfig[pair_index] == BIPOLAR_DIFFERENTIAL) {
meaning = (MAX1231_fifo_entry_t)(BIPDIF0001 + pair_index);
FIFO_meaning[index++] = meaning;
channel_index = channel_index + 2;
} else if (InputPairConfig[pair_index] == UNIPOLAR_DIFFERENTIAL) {
meaning = (MAX1231_fifo_entry_t)(UNIDIF0001 + pair_index);
FIFO_meaning[index++] = meaning;
channel_index = channel_index + 2;
} else {
meaning = (MAX1231_fifo_entry_t)(UNIAIN00 + channel_index);
FIFO_meaning[index++] = meaning;
channel_index = channel_index + 1;
}
if (meaning == UNIAIN15) break;
if (meaning == UNIDIF1415) break;
if (meaning == BIPDIF1415) break;
}
break;
case MAX1231_CONV_SCAN_T_N_15:
FIFO_meaning[index++] = TEMPERATURE;
while (index < 17) {
int pair_index = channel_index / 2;
if (InputPairConfig[pair_index] == BIPOLAR_DIFFERENTIAL) {
meaning = (MAX1231_fifo_entry_t)(BIPDIF0001 + pair_index);
FIFO_meaning[index++] = meaning;
channel_index = channel_index + 2;
} else if (InputPairConfig[pair_index] == UNIPOLAR_DIFFERENTIAL) {
meaning = (MAX1231_fifo_entry_t)(UNIDIF0001 + pair_index);
FIFO_meaning[index++] = meaning;
channel_index = channel_index + 2;
} else {
meaning = (MAX1231_fifo_entry_t)(UNIAIN00 + channel_index);
FIFO_meaning[index++] = meaning;
channel_index = channel_index + 1;
}
if (meaning == UNIAIN15) break;
if (meaning == UNIDIF1415) break;
if (meaning == BIPDIF1415) break;
}
break;
case MAX1231_CONV_SINGLE_REPEAT:
while (index < repeat_count) {
FIFO_meaning[index++] = meaning;
}
break;
case MAX1231_CONV_SINGLE_READ:
FIFO_meaning[index++] = meaning;
break;
}
/* Check for setups where AIN14-AIN15 are used for an alternate function */
if ((setup_register & 0xE0) == MAX1231_SETUP_INTCLK_CNVST) {
/* 0100xxxx AIN15 alternate function as CNVST input */
/* 0101xxxx AIN15 alternate function as CNVST input */
for (int index = 0; index < 17; index++) {
meaning = FIFO_meaning[index];
if (meaning == UNIAIN15)
FIFO_meaning[index] = UNDEFINED;
if (meaning == UNIDIF1415)
FIFO_meaning[index] = UNDEFINED;
if (meaning == BIPDIF1415)
FIFO_meaning[index] = UNDEFINED;
}
}
if ((setup_register & 0xCC) == MAX1231_SETUP_EXTREF_DIFF) {
/* 01xx11xx AIN14 alternate function as REF- input */
for (int index = 0; index < 17; index++) {
Listing 2 (Sheet 3 of 4)
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MAX1231 Evaluation System
meaning = FIFO_meaning[index];
if (meaning == UNIAIN14)
FIFO_meaning[index] = UNDEFINED;
if (meaning == UNIDIF1415)
FIFO_meaning[index] = UNDEFINED;
if (meaning == BIPDIF1415)
FIFO_meaning[index] = UNDEFINED;
}
}
}
//---------------------------------------------------------------------------
Listing 2 (Sheet 4 of 4)
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
20 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2003 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.