TS-7250-V3 ADC: Difference between revisions
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(Created page with "This board supports a 5 channels of 12-bit ADC using an integrated ADC in the i.MX6UL CPU. These are sampled up to 2MS/s between all enabled channels. All channels can sampl...") |
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| Line 9: | Line 9: | ||
! ADC Header Pin | ! ADC Header Pin | ||
! Schematic Name | ! Schematic Name | ||
! IIO device | |||
! IIO name | ! IIO name | ||
! Voltage | ! Voltage | ||
| Line 15: | Line 16: | ||
| 1 | | 1 | ||
| AN_CH1 | | AN_CH1 | ||
| iio:device0 | |||
| voltage0 | | voltage0 | ||
| 0-30VDC | | 0-30VDC | ||
| Line 21: | Line 23: | ||
| 3 | | 3 | ||
| AN_CH2 | | AN_CH2 | ||
| iio:device0 | |||
| voltage1 | | voltage1 | ||
| 0-30VDC | | 0-30VDC | ||
| Line 27: | Line 30: | ||
| 5 | | 5 | ||
| AN_CH3 | | AN_CH3 | ||
| iio:device0 | |||
| voltage5 | | voltage5 | ||
| 0-30VDC | | 0-30VDC | ||
| Line 33: | Line 37: | ||
| 7 | | 7 | ||
| AN_CH4 | | AN_CH4 | ||
| iio:device0 | |||
| voltage8 | | voltage8 | ||
| 0-30VDC | | 0-30VDC | ||
| Line 39: | Line 44: | ||
| 8 | | 8 | ||
| AN_CH5 | | AN_CH5 | ||
| iio:device0 | |||
| voltage9 | | voltage9 | ||
| 0-30VDC | | 0-30VDC | ||
Revision as of 09:53, 8 January 2020
This board supports a 5 channels of 12-bit ADC using an integrated ADC in the i.MX6UL CPU. These are sampled up to 2MS/s between all enabled channels. All channels can sample 0-10VDC, but channels 0-3 can optionally sample 0-20mA as a current loop.
These ADCs are accessed through the IIO layer in Linux. For slow speed samples the sysfs interface can be used.
cat /sys/bus/iio/devices/iio\:device0/in_voltage{0,1,5,8,9}_raw
| ADC Header Pin | Schematic Name | IIO device | IIO name | Voltage | Current loop |
|---|---|---|---|---|---|
| 1 | AN_CH1 | iio:device0 | voltage0 | 0-30VDC | 0-20mA |
| 3 | AN_CH2 | iio:device0 | voltage1 | 0-30VDC | 0-20mA |
| 5 | AN_CH3 | iio:device0 | voltage5 | 0-30VDC | 0-20mA |
| 7 | AN_CH4 | iio:device0 | voltage8 | 0-30VDC | N/A |
| 8 | AN_CH5 | iio:device0 | voltage9 | 0-30VDC | N/A |
The current loops are enabled/disabled with GPIO:
gpioset 4 7=0 # AN_CH1 voltage
gpioset 4 8=0 # AN_CH2 voltage
gpioset 4 9=0 # AN_CH3 voltage
gpioset 4 7=1 # AN_CH1 current
gpioset 4 8=1 # AN_CH2 current
gpioset 4 9=1 # AN_CH3 current
The libiio library provides simple access to the IO:
#!/usr/bin/env python3
import iio
ctx = iio.Context('local:')
dev = ctx.find_device('2198000.adc')
scan_channels = ["voltage0", "voltage1", "voltage5", "voltage8", "voltage9"]
i = int(0)
for chan_name in scan_channels:
chn = dev.find_channel(chan_name)
raw = int(chn.attrs['raw'].value)
# Scale 0-4095 to 0-2500(mV)
scaled = raw * (2.5/4095)
# Scale voltage divider on the pin
r1 = 330
r2 = 22
v = scaled / (r2 / (r1 + r2))
i += 1
print('AN_CH{}_V={:.3f}'.format(i, v))