Digital I/O (MX-V)
Overview⚓︎
MX-V has 8 digital out that can be used as either sink or source on the same pin: digital-out-source or digital-out-sink with a number.
Gpiodetect⚓︎
By using gpiodetect, a list of the GPIO chips in the system is shown.
root@mxv-pt:~# gpiodetect
gpiochip0 [209c000.gpio] (32 lines)
gpiochip1 [20a0000.gpio] (32 lines)
gpiochip10 [digital_in] (13 lines)
gpiochip2 [20a4000.gpio] (32 lines)
gpiochip3 [20a8000.gpio] (32 lines)
gpiochip4 [20ac000.gpio] (32 lines)
gpiochip5 [20b0000.gpio] (32 lines)
gpiochip6 [20b4000.gpio] (32 lines)
gpiochip7 [modem_control] (4 lines)
gpiochip8 [ncv7751] (32 lines)
gpiochip9 [gpio_overlay] (25 lines)
Digital out⚓︎
Overview⚓︎
The digital out channels (lines) have been collected in an overlay virtual chip
that also restricts the user from changing the direction of the signal (which
can usually be done for these generic I/Os).
With the gpioinfo command, the available channels are listed.
root@mxv-pt:~# gpioinfo gpio_overlay
gpiochip9 - 25 lines:
line 0: "digital-out-source-0" unused input active-high
line 1: "digital-out-source-1" unused input active-high
line 2: "digital-out-source-2" unused input active-high
line 3: "digital-out-source-3" unused input active-high
line 4: "digital-out-source-4" unused input active-high
line 5: "digital-out-source-5" unused input active-high
line 6: "digital-out-source-6" unused input active-high
line 7: "digital-out-source-7" unused input active-high
line 8: "digital-out-oc-0" unused input active-high
line 9: "digital-out-oc-1" unused input active-high
line 10: "digital-out-oc-2" unused input active-high
line 11: "digital-out-oc-3" unused input active-high
line 12: "digital-out-oc-4" unused input active-high
line 13: "digital-out-oc-5" unused input active-high
line 14: "digital-out-oc-6" unused input active-high
line 15: "digital-out-oc-7" unused input active-high
line 16: "digital-out-sink-0" unused input active-high
line 17: "digital-out-sink-1" unused input active-high
line 18: "digital-out-sink-2" unused input active-high
line 19: "digital-out-sink-3" unused input active-high
line 20: "digital-out-sink-4" unused input active-high
line 21: "digital-out-sink-5" unused input active-high
line 22: "digital-out-sink-6" unused input active-high
line 23: "digital-out-sink-7" unused input active-high
line 24: "digital-out-enable" unused input active-high
To find a specific signal, the gpiofind command can be used:
Enable digital out⚓︎
To enable digital out, the digital-out-enable line needs to be set to high.
We can use the gpioset command in combination with gpiofind in bash.
Digital out high and low⚓︎
The digital out drivers can both source and sink current. The 8 source drivers
are controlled with digital-out-source-0..7 and the sink drivers with
digital-out-sink-0..7. For a specific channel, the source and sink drivers
cannot be used at the same time.
Over-current sense⚓︎
For each digital-out-source-n there is a digital-out-oc-n which can be read to detect short-circuits.
Debugging⚓︎
/sys/kernel/debug/gpio can be read to get the kernel's view of the GPIO status.
root@mxv-pt:~# cat /sys/kernel/debug/gpio | grep -i dig
gpio-48 (DIG_OUT_LO_1 |DIG-OUT-LO ) out hi
gpio-49 (DIG_OUT_EN |DIG-OUT-EN ) out hi
gpio-64 (DIG_OUT_HI_1 |DIG-OUT-HI ) out hi
gpio-65 (DIG_OUT_HI_2 |DIG-OUT-HI ) out lo
gpio-66 (DIG_OUT_HI_3 |DIG-OUT-HI ) out lo
gpio-67 (DIG_OUT_HI_4 |DIG-OUT-HI ) out lo
gpio-68 (DIG_OUT_HI_5 |DIG-OUT-HI ) out lo
gpio-69 (DIG_OUT_HI_6 |DIG-OUT-HI ) out lo
gpio-70 (DIG_OUT_HI_7 |DIG-OUT-HI ) out lo
gpio-71 (DIG_OUT_HI_8 |DIG-OUT-HI ) out lo
gpio-72 (DIG_OUT_HI_OC_1 |DIG-OUT-HI-OC ) in hi
gpio-73 (DIG_OUT_HI_OC_2 |DIG-OUT-HI-OC ) in lo
gpio-74 (DIG_OUT_HI_OC_3 |DIG-OUT-HI-OC ) in lo
gpio-75 (DIG_OUT_HI_OC_4 |DIG-OUT-HI-OC ) in lo
gpio-76 (DIG_OUT_HI_OC_5 |DIG-OUT-HI-OC ) in hi
gpio-77 (DIG_OUT_HI_OC_6 |DIG-OUT-HI-OC ) in lo
gpio-78 (DIG_OUT_HI_OC_7 |DIG-OUT-HI-OC ) in hi
gpio-79 (DIG_OUT_HI_OC_8 |DIG-OUT-HI-OC ) in lo
gpio-166 (DIG_OUT_LO_2 |DIG-OUT-LO ) out hi
gpio-493 (digital-out-source-0|gpioset ) in hi
gpio-494 (digital-out-source-1)
gpio-495 (digital-out-source-2)
gpio-496 (digital-out-source-3)
gpio-497 (digital-out-source-4)
gpio-498 (digital-out-source-5)
gpio-499 (digital-out-source-6)
gpio-500 (digital-out-source-7)
gpio-501 (digital-out-oc-0 )
gpio-502 (digital-out-oc-1 )
gpio-503 (digital-out-oc-2 )
gpio-504 (digital-out-oc-3 )
gpio-505 (digital-out-oc-4 )
gpio-506 (digital-out-oc-5 )
gpio-507 (digital-out-oc-6 )
gpio-508 (digital-out-oc-7 )
gpio-509 (digital-out-sink-0 )
gpio-510 (digital-out-sink-1 )
gpio-511 (digital-out-enable )
Digital in⚓︎
This unit has 13 digital and analog in (adc) channels using iio devices.
gpioget $(gpiofind digital-in-1)
gpioget $(gpiofind digital-in-2)
gpioget $(gpiofind digital-in-3)
gpioget $(gpiofind digital-in-4)
gpioget $(gpiofind digital-in-5)
gpioget $(gpiofind digital-in-6)
gpioget $(gpiofind digital-in-7)
gpioget $(gpiofind digital-in-8)
# analog way to access the value
cat /sys/bus/iio/devices/iio:device0/*DIG_IN_AN_0_raw
cat /sys/bus/iio/devices/iio:device0/*DIG_IN_AN_1_raw
cat /sys/bus/iio/devices/iio:device0/*DIG_IN_AN_2_raw
cat /sys/bus/iio/devices/iio:device0/*DIG_IN_AN_3_raw
cat /sys/bus/iio/devices/iio:device0/*DIG_IN_AN_4_raw
cat /sys/bus/iio/devices/iio:device0/*DIG_IN_AN_5_raw
cat /sys/bus/iio/devices/iio:device0/*DIG_IN_AN_6_raw
cat /sys/bus/iio/devices/iio:device0/*DIG_IN_AN_7_raw
cat /sys/bus/iio/devices/iio:device0/*AN_IN_AN_1_raw
cat /sys/bus/iio/devices/iio:device0/*AN_IN_AN_2_raw
cat /sys/bus/iio/devices/iio:device0/*AN_IN_AN_3_raw
cat /sys/bus/iio/devices/iio:device0/*AN_IN_AN_4_raw
cat /sys/bus/iio/devices/iio:device0/*AN_IN_AN_5_raw