Dual Input 8-Bit Incremental ADC Datasheet DualADC8 V 1.20
001-13556 Rev. *I
Dual Input 8-Bit Incremental ADC
Copyright © 2001-2014 Cypress Semiconductor Corporation. All Rights Reserved.
PSoC® Blocks
Resources
Digital
Analog CT
API Memory (Bytes)
Analog SC
flash
RAM
Pins (per
External I/O)
CY8C29/27/24xxx, CY8CLED04/08/16, CY8CLED0xD, CY8CLED0xG, CY8C28x43, CY8C28x52, CY8CPLC20,
CY8CLED16P01
4
0
2
308
7
See application note “Analog - ADC Selection” AN2239 for other converters.
Features and Overview
Samples two inputs simultaneously
8-bit resolution
2’s complement or unsigned result
Sample rates from 122 to greater than 7600 sps
Multiple input ranges including Vss to Vdd
Integrating Converter provides good normal mode rejection
Sample rate may be changed dynamically to sync to input signal
Internal or external clock
The DualADC8 is a dual input integrating 8-bit Analog to digital converter. It can be configured to remove
unwanted high frequencies by optimizing the integrate time. Input voltages within 40 mV or less, of the
supply rails may be measured by configuring the proper reference voltage and analog ground. The output
is configurable 2’s complement or unsigned chars based on an input voltage between –Vref and +Vref
centered at AGND.
Cypress Semiconductor Corporation
Document Number: 001-13556 Rev. *I
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198 Champion Court
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San Jose, CA 95134-1709
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408-943-2600
Revised April 23, 2014
Dual Input 8-Bit Incremental ADC
Figure 1.
DualADC8 Block Diagram
Functional Description
The DualADC8 User Module is composed of two incremental ADCs in a single user module. The 16-bit
sample rate timer (PWM) is shared to reduce the required digital blocks. Since both ADCs use the same
timer, the sampling is fully synchronized. At the end of a conversion cycle, results for both inputs are
available simultaneously. Four digital PSoC blocks and two analog switch cap PSoC blocks are required,
see the figure below for a simplified schematic.
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Dual Input 8-Bit Incremental ADC
Figure 2.
Simplified Schematic of the DualADC8
The two analog blocks are configured identically as resettable integrators. Depending on the output
polarity, the reference control is configured so that the reference voltage is either added or subtracted from
the input and placed in the integrator. This reference control attempts to pull the integrator output back
towards AGND. If the integrator is operated 2Bits times and the output voltage comparator is positive “n" of
those times, the residual voltage (Vresid) at the output is as follows.
Equation 1
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Dual Input 8-Bit Incremental ADC
Equation 2
This equation states that the range of this ADC is ± Vref, the resolution (LSB) is Vref/128, and the voltage
on the output at the end of the computation is defined as the residue. Since Vresid is always less than Vref,
Vresid/256 is less than half an LSB and can be ignored. The resulting equation is listed below.
Equation 3
Example 1
For a Vref of 1.3V we can easily calculate the input voltage based on the value read from the incremental
ADC at the time the data is ready. The equation which can be used would be as follows:
Equation 4
The result of the calculation will be referenced to AGND. For a ADC data value of 200 the Voltage
measured can be calculated to be 0.73V as follows:
Equation 5
The value calculated is an ideal value and will most likely differ based on system noise and chips offsets.
To determine the code to be expected given a specific input voltage the equation can be rearranged to
give us:
Equation 6
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Dual Input 8-Bit Incremental ADC
Example 2
For a Vref of 1.3V we can easily calculate the expected ADC code based on the input Voltage. The
equation which can be used would be as follows:
Equation 7
For an input voltage of -1V below AGND the code from the ADC can be expected to be 29.53 based on
the calculation below:
Equation 8
The value calculated is an ideal value and will most likely differ based on system noise and chips offsets.
To make the integrator function as an incremental ADC, the following digital resources are utilized:
An 8-bit counter to accumulate the number of cycles that the output is positive (one per channel).
A 16-bit PWM to time the integrate time and gate the clock into the 8-bit counter (shared between both
channels).
A single DataClock is connected to the 8-bit counters, the 16-bit PWM, and the analog column clock,
which connects to the analog SC PSoC blocks. The analog column clock is actually two clocks, φ 1 and
φ 2, which are generated from the DataClock. These two additional clocks are one-fourth the frequency of
the DataClock. This means that the PWM and counter operate four times faster than required and
therefore, need to accumulate 10 bits worth of data. It is imperative, when placing this module, that you
configure it with the same clock for all blocks. Failure to do so will cause it to operate incorrectly.
The counters are implemented with an 8-bit digital block for the LSB and a software counter for the MSB.
Each time the hardware counter overflows, an interrupt is generated and the upper MSB of the counter is
incremented. This allows the DualADC8 module to be implemented with only four digital blocks instead of
six.
The sample rate is the DataClock divided by the integrate time plus the time it takes to do the result
calculations, CalcTime. The integrate time is the period when the input signal is being sampled by the
DualADC8.
Equation 9
The time it takes to calculate the result, CalcTime, varies inversely proportional with the CPU clock. The
CalcTime must be set to a value greater than what is required to calculate the result. The minimum
CalcTime is equivalent to 248 CPU cycles and must be expressed in terms of the DataClock. The
CalcTime may also be increased beyond the minimum to optimize the sample rate.
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Dual Input 8-Bit Incremental ADC
Note
The total of 1024 plus the CalcTime must not exceed 216-1 or 65,535.
Equation 10
The 16-bit PWM is programmed to output a high signal that is 1024 times the DataClock. The PWM output
will be low for the time it takes to do the minimum result calculations and to reset the integrator. This period
is controlled by the CalcTime parameter. The CalcTime can also be adjusted to help provide a more exact
sample rate in combination with the DataClock. The total period of the PWM is the sum of the integrate
time and the CalcTime.
Figure 3.
DualADC8 Timing with Respect to PWM Output
When the first reading is initiated, the PWM configuration is calculated, the integrator is reset, and the
counters are all reset to FFh. The initial delay will always be at least that of the calculation time. The PWM
is initialized only prior to the first reading. After the compare and period registers are set once, they do not
have to be re-initialized unless the resolution or calculation time is changed. When the PWM count is less
than or equal to the integrate value, the output goes high, enabling the 8-bit counters to count down. The
output of the PWM stays high until the counter reaches zero. At this point, the clock to the 8-bit counters is
disabled and the PWM interrupt is generated.
The initial value of the 8-bit software counters is set to 4 times the most negative value. Each time the 8-bit
counters overflow, the interrupt for the 8-bit counter is executed and the software counter is incremented
by one.
When the input to the ADC is greater than or equal to the most positive value, the 8-bit counters will
increment on every positive transition of the DataClock. If the input to the ADC is less than or equal to the
most negative input value, the 8-bit counters will never decrement and therefore, never generate an
interrupt. An input near analog ground under ideal conditions will allow the counter to increment half the
time. Depending on the input voltage level, the amount of interrupts from the 8-bit counters will vary from 0
to 4.
Because the DualADC8 control is interrupt based and the sample time takes a relatively long time for a
result, it is unreasonable to expect the processor to wait while a sample is being processed. The primary
communication between the ADC routine and the main program is a flag that may be polled. When the
most significant bit of DualADC8_bfStatus has a non-zero value, the new data is available in
DualADC8_iResultn (n=1,2). APIs are available to check the data flag and retrieve data.
This data handler was designed to be poll based. If an interrupt based data handler is desired, the user
may insert data handler code into the interrupt routine DualADC8_PWM16_ISR_INT, located in the
assembly file DualADC8INT.asm. The point to best insert code is clearly marked.
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Dual Input 8-Bit Incremental ADC
Channel to Channel Differences
When using the DualADC8, there will be differences between channels when measuring the same input
voltage. This difference is due to the input offset variations in the switch cap block amplifiers and the
column AGND buffers. This channel to channel offset is easily compensated for by routing the same signal
into each of the ADC channels. One of the channels can be used as the reference and the difference
between subsequent channels would be subtracted after each reading.
CPU Utilization
The DualADC8 requires CPU time to calculate the result and to increment the software counters each time
the hardware counters overflow. The CPU overhead is dependent on three variables: CPU clock,
DataClock, and input voltage. At first it may seem odd that input voltage affects the CPU overhead for an
ADC. Input voltages that are near or lower than –Vref require very little CPU overhead. Input voltages that
are near or greater than +Vref require more CPU overhead. The equations below assume the input signal
is the same for both inputs. To calculate the CPU cycles required for a given input, reference the following
equations.
Equation 11
To calculate the maximum CPU cycles set Vin to Vref, and reference the following equation.
Equation 12
To calculate the percent CPU utilization of the DualADC8, reference the following equation.
Equation 13
Setting the sample rate to 1000 samples/sec and the CPU clock to 12 MHz, then in the equation below,
about 6.5% of the CPU is utilized.
Equation 14
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Dual Input 8-Bit Incremental ADC
The graph below shows CPU utilization for the supported sample rates and resolutions. The default CPU
speed is set to 12 MHz.
Figure 4.
CPU Usage versus Sample Rate
Frequency Rejection
By selecting the proper integrate time, specific noise sources may be rejected. To reject a noise source
and its harmonics, select an integrate time that is equal to an integral cycle of the noise signal. If more
than one signal is to be rejected, select an integrate time that is equal to an integral cycle of both signals.
For example, if noise caused by 50 Hz and 60 Hz signals is to be rejected, select a period that contains an
integral number of both the 50 Hz and 60 Hz signals.
Equation 15
An IntegrateTime of 100 ms will reject both 50 Hz and 60 Hz, and any harmonics of these signals. Next,
calculate the DataClock required to generate the proper IntegrateTime.
Equation 16
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Dual Input 8-Bit Incremental ADC
Notice that the CalcTime is not used in this calculation, although it affects the sample rate. The
IntegrateTime is the period when the DualADC8 is actually sampling the input voltage. The sample rate is
based on the IntegrateTime and the time it takes to calculate the result.
Example
An IntegrateTime of 5ms is required for a given application, therefore the data clock must be as follows.
Equation 17
The CalcTime, in terms of the Data Clock, must be calculated from the DataClock and the CPU Clock. If
the CPU clock is 12 MHz, the minimum calculation time would be as follows.
Equation 18
This CalcTime should be rounded up to the nearest whole number, in this example it is 5. To determine the
sample rate, proceed as follows.
Equation 19
If a longer sample rate is desired, the CalcTime may be increased until the CalcTime + 1024 is less than or
equal to 216 – 1 (65535).
DC and AC Electrical Characteristics
The following values are indicative of expected performance and based on initial characterization data.
Unless otherwise specified in the table below, TA = 25°C, Vdd = 5.0V, Power HIGH, Op-Amp bias LOW,
output referenced to 2.5V external Analog Ground on P2[4] with 1.25 external Vref on P2[6].
Table 1.
5.0V DualADC8 DC and AC Electrical Characteristics CY8C29/27/24xxx, CY8CLED04/08/16,
CY8CLED0xD, CY8CLED0xG, CY8C28x43, CY8C28x52Family of PSoC Devices
Parameter
Typical
Limit
Units
Conditions and Notes
Input
Input Voltage Range
---
Vss to Vdd
Input Capacitance1
3
---
pF
Input Impedance
1/(C*clk)
---
W
Resolution
---
8
Bits
Sample Rate
---
122 to 7800
SPS
SNR
47
---
dB
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Ref Mux = Vdd/2 ± Vdd/2
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Dual Input 8-Bit Incremental ADC
Parameter
Typical
Limit
Units
Conditions and Notes
DC Accuracy
DNL
0.25
---
LSB
INL
1.0
---
LSB
9
---
mV
Including Reference Gain Error
3.0
--
% FSR
Excluding Reference Gain Error2
0.1
--
% FSR
Low Power
370
---
uA
Med Power
1200
---
uA
High Power
4000
---
uA
Data Clock
---
0.125 to 8.0
MHz
Offset Error
Column clock 2 MHz
Gain Error
Operating Current
Input to digital blocks and
analog column clock
The following values are indicative of expected performance and based on initial characterization data.
Unless otherwise specified in the table below, all limits guaranteed for TA = 25°C, Vdd = 3.3V, Power
HIGH, Op-Amp bias LOW, output referenced to 1.64V external Analog Ground on P2[4] with 1.25 external
Vref on P2[6].
Table 2.
3.3V DualADC8 DC and AC Electrical Characteristics, CY8C29/27/24xxx, CY8CLED04/08/16,
CY8CLED0xD, CY8CLED0xG, CY8C28x43, CY8C28x52Family of PSoC Devices
Parameter
Typical
Limit
Units
Conditions and Notes
Input
Input Voltage Range
---
Vss to Vdd
Ref Mux = Vdd/2 ± Vdd/2
Input Capacitance1
3
---
pF
Input Impedance
1/(C*clk)
---
W
Resolution
---
8
Bits
Sample Rate
---
122 to 7800
SPS
SNR
47
---
dB
DNL
0.25
---
LSB
INL
1.0
---
LSB
4
---
mV
DC Accuracy
Offset Error
Column clock 2 MHz
Gain Error
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Dual Input 8-Bit Incremental ADC
Parameter
Typical
Limit
Units
Including Reference Gain Error
3.0
--
% FSR
Excluding Reference Gain Error2
0.4
--
% FSR
Low Power
300
---
uA
Med Power
1000
---
uA
High Power
3800
---
uA
Data Clock
---
0.125 to 8.0
MHz
Conditions and Notes
Operating Current
Input to digital blocks and
analog column clock
Electrical Characteristics Notes
1. Includes I/O pin.
2. Reference Gain Error measured by comparing the external reference to VRefHigh and VRefLow routed
through the test mux and back out to a pin.
3. Typical values represent parametric norm at +25°C.
4. Input voltages above the maximum will generate a maximum positive reading. Input voltages below the
minimum will generate a maximum negative reading.
5. User module only, not including I/O pin.
6. The input capacitance or impedance is only applicable when input to analog block is directly to a pin.
7. C = input capacitance, clk = data clock (Analog Column Clock).
8. Specifications are for sample rates of 100 sps and a maximum data clock of 8 MHz, unless otherwise
noted. Sample rate is dependent on both data clock and resolution.
9. SNR = Ratio of power of full scale single tone divided by total noise integrated to Fsample/2.
Placement
The ADC (switch cap) blocks can be placed in any of the switched capacitor PSoC blocks. They must be
able to each exclusively drive the comparator bus for the particular column in which it is placed. In other
words, each of the two blocks must be in a different column and can not share a column with another
switch cap block that connects to the comparator bus.
The counter blocks may be placed in any available digital block, but the PWM16 may only be placed in
specific locations. In the CY8C27xxx device family possible placements for the PWB16 (LSB/MSB) are
DBB00/DBB01, DBB01/DCB02, DBB10/DBB11, and DBB11/DCB12. In the CY8C29/24/22xxx device
families the PWM16 can be placed in any two consecutive digital blocks.
The two counter blocks and PWM block each have an interrupt service routine. It is desirable that the
counter block have a higher interrupt priority than the PWM16 block. Therefore, it is recommended that the
counter blocks are placed in a lower digital block position than the PWM16 block.
Note
When initially selecting the DualADC8, a warning may appear that states “Resource allocation
prevents placement." This warning is displayed if the original placement has two ADC blocks in the
same column. Simply move each ADC block to its own column.
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Dual Input 8-Bit Incremental ADC
Parameters and Resources
ADC Input1, ADC Input2
The selection of the ADC Input is done after the analog PSoC block is placed. The eight switched cap
blocks have different input selections. Each can be connected to most of its neighbors, while some
can be connected directly to external input pins. Placement of the analog block must be done with
some consideration of how to get an input signal to it. Some placements allow inputs to be routed
directly from package pins to the input. These direct connections allow inputs that are within 40 mV
of the supply rails to be measured accurately. Signals may also be routed through one of the column
muxes, through one of the CT block test muxes, and onto an analog column where the DualADC8
can also measure signals near the power supply rails. There is one selection for each of the two ADC
inputs.
ClockPhase1, ClockPhase2
The selection of the Clock Phase is used to synchronize the output of one switched capacitor analog
PSoC block to the input of another. The switched cap analog PSoC blocks use a two-phase clock (φ 1,
φ 2) to acquire and transfer signal. Typically, the input to the DualADC8 is sampled on φ 1, the Normal
setting. A problem arises in that many of the user modules auto-zero their output during φ 1 and only
provide a valid output during φ 2. If such a module’s output is fed to the DualADC8’s input, the
DualADC8 acquires an auto-zeroed output, instead of a valid signal. The Clock Phase selection
allows the phases to be swapped so that the input signal is now acquired during φ 2, the Swapped
setting. There is one selection for each of the two switch cap blocks.
Clock and Integrator Column Clock
The DataClock determines the sample rate and the signal sample window. This clock must be routed
to the clock input of the counter block, the 16-bit PWM block, and the column clock for the column
containing the integrator.
Note
The column clocks of the integrator switch cap blocks must be manually set to the SAME clock. It
is imperative that the same clock be used for all six blocks or the DualADC8 User Module will not
function correctly.
This parameter setting will only set the clock to the counter block and the PWM block. This clock may
be any source with a clock rate between 125 kHz and 8 MHz.
Equation 20
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Dual Input 8-Bit Incremental ADC
The graph below shows possible sample rates for each of the resolution options for the DualADC8.
Figure 5.
Samples per Second versus Data Clock
Ref Mux Global Resource
The most important global resource when dealing with analog to digital converters (ADC) is the
RefMux. The setting of the RefMux determines the usable input voltage range of the ADC. The
following table shows the ranges for a Vdd of 5 and 3.3 volts.
Table 3.
CY8C29/27/24xxx, CY8CLED04/08/16, CY8CLED0xD, CY8CLED0xG, CY8C28x43, CY8C28x52 Input
Voltage Ranges for Each Ref Mux Setting
RefMux Setting
Vdd = 5 Volts
Vdd = 3.3 Volts
(Vdd/2) ± BandGap
1.2 < Vin < 3.8
0.35 < Vin < 2.95
(Vdd/2) ± (Vdd/2)
0 < Vin < 5
0 < Vin < 3.3
BandGap ± BandGap
0 < Vin < 2.6
0 < Vin < 2.6
(1.6*BandGap) ± (1.6*BandGap)
0 < Vin < 4.16
NA
(2*BandGap) ± BandGap
1.3 < Vin < 3.9
NA
(2*BandGap) ± P2[6]
(2.6 - VP2[6]) < Vin < (2.6 + VP2[6])
NA
P2[4] ± BandGap
(VP2[4] - 1.3) < Vin < (VP2[4] + 1.3)
(VP2[4] - 1.3) < Vin < (VP2[4] + 1.3)
P2[4] ± P2[6]
(VP2[4]-VP2[6]) < Vin < (VP2[4]+VP2[6])
(VP2[4]-VP2[6]) < Vin < (VP2[4]+VP2[6])
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Dual Input 8-Bit Incremental ADC
DataFormat
This selection determines in what format the result will be returned. If “Signed" is selected and “N" is
the selected resolution, the result will range from –128 to +127. If “Unsigned" is selected, the result
will be from 0 to 255.
Interrupt Generation Control
There is an additional parameter that becomes available when the Enable interrupt generation control
check box in PSoC Designer is checked. This is available under Project > Settings > Chip Editor.
Interrupt Generation Control is important when multiple overlays are used with interrupts shared by
multiple user modules across overlays:
IntDispatchMode
The IntDispatchMode parameter is used to specify how an interrupt request is handled for interrupts
shared by multiple user modules existing in the same block but in different overlays. Selecting
“ActiveStatus" causes firmware to test which overlay is active before servicing the shared interrupt
request. This test occurs every time the shared interrupt is requested. This adds latency and also
produces a nondeterministic procedure of servicing shared interrupt requests, but does not require
any RAM. Selecting “OffsetPreCalc" causes firmware to calculate the source of a shared interrupt
request only when an overlay is initially loaded. This calculation decreases interrupt latency and
produces a deterministic procedure for servicing shared interrupt requests, but at the expense of a
byte of RAM.
Application Programming Interface
API routines are provided to initialize, configure, start sampling, stop, and read the resultant data from the
ADC.
Note
For Large Memory Model devices, it is also the caller's responsibility to preserve any value in the
CUR_PP, IDX_PP, MVR_PP, and MVW_PP registers. Even though some of these registers may
not be modified now, there is no guarantee that will remain the case in future releases.
DualADC8_Start
Description:
Performs all required initialization for this user module and sets the power level for the switched
capacitor PSoC block.
C Prototype:
void
DualADC8_Start (BYTE bPowerSetting)
Assembly:
mov
call
A, DualADC8_HIGHPOWER
DualADC8_Start
Parameters:
PowerSetting: One byte that specifies the power level. Following reset and configuration, the analog
PSoC block assigned to DualADC8 is powered down. Symbolic names provided in C and assembly,
and their associated values, are given in the following table.
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Dual Input 8-Bit Incremental ADC
Symbolic Name
Value
DualADC8_OFF
0
DualADC8_LOWPOWER
1
DualADC8_MEDPOWER
2
DualADC8_HIGHPOWER
3
Power level has an effect on analog performance. The correct power setting is sensitive to the sample
rate of the data clock and has to be determined for each application. It is recommended that you start
your development with full power selected. Testing can later be done to determine how low you can
set the power setting.
Return Value:
None
Side Effects:
The A and X registers may be modified by this or future implementations of this function. The same
is true for all RAM page pointer registers in the Large Memory Model (CY8C29xxx). When necessary,
it is the calling function's responsibility to preserve the values across calls to fastcall16 functions.
DualADC8_SetPower
Description:
Sets the power level for the switched capacitor PSoC block.
C Prototype:
void
DualADC8_SetPower (BYTE bPowerSetting)
Assembly:
mov
A, [bPowerSetting]
lcall DualADC8_SetPower
Parameters:
PowerSetting: Same as the PowerSetting parameter used for the Start API routine. Allows the user
to change the power level while operating the ADC.
Return Value:
None
Side Effects:
The A and X registers may be modified by this or future implementations of this function. The same
is true for all RAM page pointer registers in the Large Memory Model (CY8C29xxx). When necessary,
it is the calling function's responsibility to preserve the values across calls to fastcall16 functions.
DualADC8_Stop
Description:
Sets the power level on the switched capacitor integrator block to 0ff. This is done when the
DualADC8 in not being used and the user wants to save power. This routine powers down the analog
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Dual Input 8-Bit Incremental ADC
switch capacitor block and disables the digital blocks. To achieve the lowest power level, the clock
should be removed from the digital blocks as well.
C Prototype:
void
DualADC8_Stop(void)
Assembly:
lcall
DualADC8_Stop
Parameters:
None
Return Value:
None
Side Effects:
The A and X registers may be modified by this or future implementations of this function. The same
is true for all RAM page pointer registers in the Large Memory Model (CY8C29xxx). When necessary,
it is the calling function's responsibility to preserve the values across calls to fastcall16 functions.
DualADC8_GetSamples
Description:
Initializes and starts the ADC algorithm to collect samples. Remember to enable global interrupts by
calling the M8C_EnableGInt macro call defined in M8C.inc or M8C.h.
C Prototype:
void
DualADC8_GetSamples (void)
Assembly:
lcall
DualADC8_GetSamples
Parameters:
None:
Return Value:
None
Side Effects:
The A and X registers may be modified by this or future implementations of this function. The same
is true for all RAM page pointer registers in the Large Memory Model (CY8C29xxx). When necessary,
it is the calling function's responsibility to preserve the values across calls to fastcall16 functions.
Currently, only the CUR_PP page pointer register is modified.
DualADC8_StopAD
Description:
Immediately halts the ADC.
C Prototype:
void
DualADC8_StopAD(void)
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Dual Input 8-Bit Incremental ADC
Assembly:
lcall
DualADC8_StopAD
Parameters:
None
Return Value:
None
Side Effects:
The A and X registers may be modified by this or future implementations of this function. The same
is true for all RAM page pointer registers in the Large Memory Model (CY8C29xxx). When necessary,
it is the calling function's responsibility to preserve the values across calls to fastcall16 functions.
DualADC8_fIsDataAvailable
DualADC8_fIsData
DualADC8_flsDataAvailable is identical to DualADC8_flsData listed below.
Description:
Returns non-zero when a data conversion is complete and data is available for reading.
C Prototype:
BYTE
DualADC8_fIsData(void)
Assembly:
lcall
DualADC8_fIsData
Parameters:
None
Return Value:
Returns non-zero when data is available.
Side Effects:
The A and X registers may be modified by this or future implementations of this function. The same
is true for all RAM page pointer registers in the Large Memory Model (CY8C29xxx). When necessary,
it is the calling function's responsibility to preserve the values across calls to fastcall16 functions.
Currently, only the CUR_PP page pointer register is modified.
DualADC8_cGetData1
Description:
Returns last converted data for ADC Input1. DualADC8_fIsDataAvailable() should be called prior to
getting the data, to ensure that the data is valid. Data must be retrieved before the next conversion
cycle is completed or else the data will be overwritten. There is a possibility that the returned data will
be corrupted if the call to this function is done exactly at the end of an integration period. It is therefore
highly recommended that the data retrieval be done at a higher frequency than the sampling rate, or
if that cannot be guaranteed that interrupts be turned off before calling this function.
C Prototype:
char
DualADC8_cGetData1(void)
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Dual Input 8-Bit Incremental ADC
Assembly:
lcall
DualADC8_cGetData1
Parameters:
None
Return Value:
Converted value is returned. In assembler, the result in returned in the accumulator.
Side Effects:
The A and X registers may be modified by this or future implementations of this function. The same
is true for all RAM page pointer registers in the Large Memory Model (CY8C29xxx). When necessary,
it is the calling function's responsibility to preserve the values across calls to fastcall16 functions.
Currently, only the CUR_PP page pointer register is modified.
DualADC8_cGetData2
Description:
Returns last converted data for ADC Input2. DualADC8_fIsDataAvailable() should be called prior to
getting the data, to ensure that the data is valid. Data must be retrieved before the next conversion
cycle is completed or else the data will be overwritten. There is a possibility that the returned data will
be corrupted if the call to this function is done exactly at the end of an integration period. It is therefore
highly recommended that the data retrieval be done at a higher frequency than the sampling rate, or
if that cannot be guaranteed that interrupts be turned off before calling this function.
C Prototype:
char
DualADC8_cGetData2(void)
Assembly:
lcall
DualADC8_cGetData2
Parameters:
None
Return Value:
Converted value is returned. In assembler, the result is returned in the accumulator.
Side Effects:
The A and X registers may be modified by this or future implementations of this function. The same
is true for all RAM page pointer registers in the Large Memory Model (CY8C29xxx). When necessary,
it is the calling function's responsibility to preserve the values across calls to fastcall16 functions.
Currently, only the CUR_PP page pointer register is modified.
Note
The functions DualADC8_ClearFlag, DualADC8_cGetData1ClearFlag, and
DualADC8_cGetData2ClearFlag all clear the same flag. They are included to provide the greatest
amount of flexibility when clearing the conversion complete flag. When the A/D conversion is complete, the user may choose to ignore the result of one or both channels and simply clear the flag
without retrieving the data.
Document Number: 001-13556 Rev. *I
Page 18 of 28
Dual Input 8-Bit Incremental ADC
DualADC8_ClearFlag
Description:
Clears Data Available flag.
C Prototype:
void
DualADC8_ClearFlag(void)
Assembly:
lcall
DualADC8_ClearFlag
Parameters
None
Return Value:
None
Side Effects:
The A and X registers may be modified by this or future implementations of this function. The same
is true for all RAM page pointer registers in the Large Memory Model (CY8C29xxx). When necessary,
it is the calling function's responsibility to preserve the values across calls to fastcall16 functions.
Currently, only the CUR_PP page pointer register is modified.
DualADC8_cGetData1ClearFlag
Description:
Returns last converted data for ADC Input1 and clears the Data Available flag.
DualADC8_fIsDataAvailable() should be called prior to getting the data, to ensure that the data is
valid. Data must be retrieved before the next conversion cycle is completed or else the data will be
overwritten. There is a possibility that the returned data will be corrupted if the call to this function is
done exactly at the end of an integration period. It is therefore highly recommended that the data
retrieval be done at a higher frequency than the sampling rate, or if that cannot be guaranteed that
interrupts be turned off before calling this function.
C Prototype:
char
DualADC8_cGetData1ClearFlag(void)
Assembly:
lcall
DualADC8_cGetData1ClearFlag
Parameters:
None
Return Value:
Converted value is returned. In assembler, the result is returned in the accumulator.
Side Effects:
The A and X registers may be modified by this or future implementations of this function. The same
is true for all RAM page pointer registers in the Large Memory Model (CY8C29xxx). When necessary,
it is the calling function's responsibility to preserve the values across calls to fastcall16 functions.
Currently, only the CUR_PP page pointer register is modified.
Document Number: 001-13556 Rev. *I
Page 19 of 28
Dual Input 8-Bit Incremental ADC
DualADC8_cGetData2ClearFlag
Description:
Returns last converted data for ADC Input2 and clears the Data Available flag.
DualADC8_fIsDataAvailable() should be called prior to getting the data, to ensure that the data is
valid. Data must be retrieved before the next conversion cycle is completed or else the data will be
overwritten. There is a possibility that the returned data will be corrupted if the call to this function is
done exactly at the end of an integration period. It is therefore highly recommended that the data
retrieval be done at a higher frequency than the sampling rate, or if that cannot be guaranteed that
interrupts be turned off before calling this function.
C Prototype:
char
DualADC8_cGetData2ClearFlag(void)
Assembly:
lcall
DualADC8_cGetData2ClearFlag
Parameters:
None
Return Value:
Converted value is returned. In assembler, the result is returned in the accumulator.
Side Effects:
The A and X registers may be modified by this or future implementations of this function. The same
is true for all RAM page pointer registers in the Large Memory Model (CY8C29xxx). When necessary,
it is the calling function's responsibility to preserve the values across calls to fastcall16 functions.
Currently, only the CUR_PP page pointer register is modified.
DualADC8_SetCalcTime
Description:
The CalcTime is the amount of time it takes the CPU to calculate intermediate integration result before
the next integrate cycle can start. The time it takes to calculate the result “CalcTime" varies inversely
proportionally with the CPU clock. This value must be in terms of the Data Clock. Minimum CPU calculation time is 248 CPU clocks. CalcTime may also be increased to optimize the sample rate. Care
should be taken to make sure the CalcTime + of 1024 does not exceed 216-1 or 65,535. Below is an
equation to determine what the CalcTime should be set to;
Equation 21
For example, if the DataClock is set to 1.5 MHz and the CPU is running at 12 MHz, the CalcTime
should be set to greater than or equal to 31. See equation below.
Equation 22
Document Number: 001-13556 Rev. *I
Page 20 of 28
Dual Input 8-Bit Incremental ADC
C Prototype:
INT DualADC8_SetCalcTime(int iCalcTime)
Assembly:
mov
A, [iCalcTimeLSB]
mov
X, [iCalcTimeMSB]
lcall DualADC8_SetCalcTime
Parameters:
Calctime, see equations above.
Return Value:
None.
Side Effects:
The A and X registers may be modified by this or future implementations of this function. The same
is true for all RAM page pointer registers in the Large Memory Model (CY8C29xxx). When necessary,
it is the calling function's responsibility to preserve the values across calls to fastcall16 functions.
Currently, only the CUR_PP page pointer register is modified.
Sample Firmware Source Code
Sample project written in assembly code.
;;; Sample ASM Code for the DualADC8
;;;
;;; Continuously sample using the DUALADC8 and store the values in RAM.
;;;
;;; Note: For this example the instance name of this ADC is: “DualADC8"
;;;
;;;
If a different instance name is selected, the variables must
;;;
change to reflect this.
;;;
include "M8C.inc"
include "DualADC8.inc"
;; Create storage for readings
area bss(RAM)
cResult1:
BLK 1
; ADC1 result storage
cResult2:
BLK 1
; ADC2 result storage
export cResult1
; Export results in case they are
export cResult2
; used elsewhere.
area text(ROM,REL)
export _main
_main:
M8C_EnableGInt
mov
A, 100
mov
X, 0
call DUALADC8_SetCalcTime
; Enable interrupts
; Set CalcTime to 100
;
mov
; Set Power and Enable A/D
A, DUALADC8_HIGHPOWER
Document Number: 001-13556 Rev. *I
Page 21 of 28
Dual Input 8-Bit Incremental ADC
call
DUALADC8_Start
call
DUALADC8_GetSamples
; Start A/D in continuous sampling mode
;A/D conversion loop
loop1:
wait:
call
jz
call
; Poll until data is complete
DUALADC8_fIsDataAvailable
wait
DUALADC8_ClearFlag
; Reset flag
call
mov
DUALADC8_cGetData1
[cResult1],A
; Get ADC1 Data
; Store value
call
mov
jmp
DUALADC8_cGetData2
[cResult2],A
loop1
; Get ADC2 Data
; Store value
A sample project written in C follows.
//---------------------------------------------------------------------// Sample C Code for the DualADC8
// Continuously Sample and call a user function with the data.
// This example differs from the ASM example, in that the DataAvailable
// flag is automatically cleared when the second value is read, instead of
// clearing the flag prior to reading the data.
//
//----------------------------------------------------------------------#include "DualADC8.h"
extern void User_Function(char cResult1, char cResult2);
void main(void)
{
char cResult1, cResult2;
M8C_EnableGInt;
DUALADC8_Start(DUALADC8_HIGHPOWER);
DUALADC8_SetCalcTime(100);
DUALADC8_GetSamples();
//
//
//
//
Enable global interrupts
Turn on Analog section
Set CalcTime to 100
Start ADC
for(;1;)
{
while(DUALADC8_fIsDataAvailable == 0);
// Wait for data to be ready
cResult1 = DUALADC8_cGetData1();
// Get Data from ADC Input1
cResult2 = DUALADC8_cGetData2ClearFlag(); // Get Data from ADC Input2
// and clear data ready flag
Document Number: 001-13556 Rev. *I
Page 22 of 28
Dual Input 8-Bit Incremental ADC
User_Function(cResult1,cResult2);
// User function to use data
}
}
Configuration Registers
These registers are configured by the initialization and API library. The user does not have to change or
read these registers directly. This section is supplied as a reference only.
The ADC is a switched capacitor PSoC block. It is configured to make an analog modulator. To build the
modulator, the block is configured to be an integrator with reference feedback that converts the input value
into a digital pulse stream. The input multiplexer determines what signal is digitized.
Table 4.
Block ADC1: Register CR0
Bit
Value
Table 5.
7
1
0
5
0
4
1
3
0
2
0
1
0
0
0
Block ADC1: Register CR1
Bit
Value
6
7
6
5
ACMux, AMux
4
0
3
0
2
0
1
0
0
0
ACMux is used when block is placed in a type ‘A’ block. AMux is used when block is placed in a type ‘B’
block. Both field values depend on how the user connects the input.
Table 6.
Block ADC1: Register CR2
Bit
Value
Table 7.
7
0
1
5
1
4
0
3
0
2
0
1
0
0
0
Block ADC1: Register CR3
Bit
Value
6
7
1
6
1
5
1
4
FSW0
3
0
2
0
1
0
0
0
FSW0 is used by the PWM interrupt handler and various APIs. A ‘0’ value causes the ADC to be a
disabled integrator. A ‘1’ value causes the ADC to be an enabled integrator.
Table 8.
Block ADC2: Register CR0
Bit
Value
Table 9.
7
1
0
5
0
4
1
3
0
2
0
1
0
0
0
Block ADC2: Register CR1
Bit
Value
6
7
6
5
ACMux, AMux
4
0
3
0
2
0
1
0
0
0
ACMux is used when the block is placed in a type ‘A’ block. AMux is used when the block is placed in a
type ‘B’ block. Both field values depend on how the user connects the input.
Table 10.
Block ADC2: Register CR2
Bit
Value
7
0
6
1
Document Number: 001-13556 Rev. *I
5
1
4
0
3
0
2
0
1
0
0
0
Page 23 of 28
Dual Input 8-Bit Incremental ADC
Table 11.
Block ADC2: Register CR3
Bit
Value
7
1
6
1
5
1
4
FSW0
3
0
2
0
1
0
0
0
FSW0 is used by the TMR interrupt handler and various APIs. A ‘0’ value causes the ADC to be a disabled
integrator. A ‘1’ value causes the ADC to be an enabled integrator.
The PWM16 is a digital PsoC block that is used to control the integration time of the ADC. The compare
value is set to 2Bits+2 and the period is set to the CalcTime plus the compare value.
Table 12.
Block PWM16_MSB: Register Function
Bit
Value
7
0
6
0
5
1
4
Compare
Type
3
Interrupt
Type
2
0
1
0
0
1
Compare Type is a flag that indicates whether the capture comparison is “equal to or less than" or “less
than." Interrupt Type is a flag that indicates whether to trigger the interrupt on the capture event or the
terminal condition. Both parameters are set in the Device Editor.
Table 13.
Block PWM16_LSB: Register Function
Bit
Value
7
0
6
0
5
0
4
Compare
Type
3
0
2
0
1
0
0
1
Compare Type is a flag that indicates whether the compare function is set to “equal to or less than" or “less
than." This parameter is set in the Device Editor.
Table 14.
Block PWM16_MSB: Register Input
Bit
Value
7
0
6
0
5
1
4
1
3
2
1
0
Clock
Clock selects the input clock from one of 16 sources. This parameter is set in the Device Editor.
Table 15.
Bit
Value
Block PWM16_LSB: Register Input
7
6
Enable
5
4
3
2
1
0
Clock
Enable selects data input from one of 16 sources and Clock selects clock input from one of 16 sources.
Both parameters are set in the Device Editor.
Document Number: 001-13556 Rev. *I
Page 24 of 28
Dual Input 8-Bit Incremental ADC
Table 16.
Block PWM16_MSB: Register Output
Bit
Value
7
0
6
0
5
0
4
0
3
0
2
Output
Enable
1
0
Output Sel
Output Enable is the flag that indicates the output is enabled. Output Sel is the flag that indicates where
the output of the PWM16 will be routed. Both parameters are set in the Device Editor.
Table 17.
Block PWM16_LSB: Register Output
Bit
Value
Table 18.
Bit
Value
7
0
6
0
5
0
4
0
3
0
2
0
1
0
0
0
Block PWM16_MSB: Count Register DR0
7
6
5
4
3
2
1
0
1
0
1
0
Count(MSB)
Count is the PWM16 MSB down PWM. It can be read using the PWM16 API.
Table 19.
Bit
Value
Block PWM16_LSB: Count Register DR0
7
6
5
4
3
2
Count(LSB)
Count is the PWM16 LSB down PWM. It can be read using the PWM16 API.
Table 20.
Bit
Value
Block PWM16_MSB: Period Register DR1
7
6
5
4
3
2
Period(MSB)
Period holds the MSB of the period value that is loaded into the Counter register, upon enable or terminal
count condition. It can be set by the Device Editor and the PWM16 API.
Table 21.
Bit
Value
Block PWM16_LSB: Period Register DR1
7
6
5
4
3
2
1
0
Period(LSB)
Period holds the LSB of the period value that is loaded into the Counter register, upon enable or terminal
count condition. It can be set by the Device Editor and the PWM16 API.
Table 22.
Bit
Value
Block PWM16_MSB: Pulse Width Register DR2
7
6
5
4
3
2
1
0
Pulse Width(MSB)
PulseWidth holds the MSB of the pulse width value used to generate the compare event. It can be set by
the Device Editor and the PWM16 API.
Document Number: 001-13556 Rev. *I
Page 25 of 28
Dual Input 8-Bit Incremental ADC
Table 23.
Block PWM16_LSB: Pulse Width Register DR2
Bit
Value
7
6
5
4
3
2
1
0
Pulse Width(LSB)
PulseWidth holds the LSB of the pulse width value used to generate the compare event. It can be set by
the Device Editor and the PWM16 API.
Table 24.
Block PWM16_MSB: Control Register CR0
Bit
Value
7
0
6
0
5
0
4
0
3
0
2
0
1
0
0
Start/
Stop(0)
Start/Stop is controlled by the LSB control register value, set to zero.
Table 25.
Block PWM16_LSB: Control Register CR0
Bit
Value
7
0
6
0
5
0
4
0
3
0
2
0
1
0
0
Start/ Stop
Start/Stop indicates that the PWM16 is enabled when set. It is modified by using the PWM16 API
The CNT is a digital PSoC block configured as a counter. When the value in DR0 counts down to terminal
count, an interrupt is called to decrement a higher value software counter and CNT reloads from DR1. The
data is outputted through DR2.
Table 26.
Block CNT1: Register Function
Bit
Value
Table 27.
7
0
0
5
1
4
0
3
0
2
0
1
0
0
1
Block CNT1: Register Input
Bit
Value
6
7
6
5
4
Data
3
2
1
0
Clock
Data selects the column comparator where the ADC block has been placed. Clock selects the input clock
from one of 16 sources and is set in the Device Editor.
Table 28.
Block CNT1: Register Output
Bit
Value
Table 29.
Bit
Value
7
0
6
0
5
0
4
0
3
0
2
0
1
0
0
0
Block CNT1: Register DR0
7
6
5
4
3
2
1
0
Count Value
Document Number: 001-13556 Rev. *I
Page 26 of 28
Dual Input 8-Bit Incremental ADC
Table 30.
Block CNT1: Register DR1
Bit
Value
Table 31.
7
1
1
5
1
4
1
3
1
2
1
1
1
0
1
Block CNT1: Register DR2
Bit
Value
6
7
6
5
4
3
2
1
0
2
1
0
Data Out
Data Out is the register used by the API to get the counter value.
Table 32.
Block CNT1: Register CR0
Bit
Value
7
0
6
0
5
0
4
0
3
0
0
0
Enable
Enable enables the CNT. It is modified and controlled by the DualADC8 API
Table 33.
Block CNT2: Register Function
Bit
Value
Table 34.
7
0
0
5
1
4
0
3
0
2
0
1
0
0
1
Block CNT2: Register Input
Bit
Value
6
7
6
5
4
Data
3
2
1
0
Clock
Data selects the column comparator where the ADC block has been placed. Clock selects the input clock
from one of 16 sources and is set in the Device Editor.
Table 35.
Block CNT2: Register Output
Bit
Value
Table 36.
7
0
Table 37.
7
0
4
0
3
0
2
0
1
0
0
0
6
5
4
3
2
1
0
5
4
3
2
1
0
Count Value
Block CNT2: Register DR1
Bit
Value
0
5
Block CNT2: Register DR0
Bit
Value
6
7
1
6
1
Document Number: 001-13556 Rev. *I
1
1
1
1
1
1
Page 27 of 28
Dual Input 8-Bit Incremental ADC
Table 38.
Block CNT2: Register DR2
Bit
7
Value
6
5
4
3
2
1
0
2
1
0
Data Out
Data Out is the register used by the API to get the counter value.
Table 39.
Block CNT2: Register CR0
Bit
7
Value
0
6
0
5
0
4
0
3
0
0
0
Enable
Enable enables the CNT. It is modified and controlled by the DualADC8 API.
Table 40.
Register: INT_MSK1
Bit
7
6
5
4
3
2
1
0
Value
The mask bits corresponding to the TMR block and CNT block are set here to enable their respective
interrupts. The actual mask values are determined by the placement position of each block.
Version History
Version
1.1
Originator
DHA
Description
Added DRC to check if:
1. The source clock is different in digital and analog resources.
2. The ADC Clock is higher than CPU Clock.
1.20
DHA
Restored VC3 as the source for the data clock.
1.20.b
MYKZ
Added design rules check for the situation when ADC clock is faster than 8MHz.
Note
PSoC Designer 5.1 introduces a Version History in all user module datasheets. This section documents high level descriptions of the differences between the current and previous user module versions.
Document Number: 001-13556 Rev. *I
Revised April 23, 2014
Page 28 of 28
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