Hello,
Old school board here and so on…
6.1.80-ti-r34BeagleBoard.org Debian Bookworm Minimal Image 2024-05-29I figured I would try an updated version of the images from a known source…
Anyway, when I type:
import time
import gpiod
...
# Code below
I receive an error about gpiod not being installed but when I check with apt, it is installed along with libgpiod-dev.
Seth
P.S. Please send guidance.
I might be completely off target here, but isn’t libgpiod a C binding?
Are you looking for the python equivalent, perchance?
Try to search for python install gpiod and see if something interesting pops up.
gpiod is for python3 and libgpiod-dev is the C versioning…yes.
Seth
P.S. I changed my set up again by changing the image and now I have kernel 5.10.x. I am goin’ to use sysfs and see how far I get.
Sorry if I didn’t express myself clearly enough.
I don’t think you can see installed python library packages with apt.
The apt gpiod is a daemon; hence why I wanted you to see if pip says installed…
Again, python isn’t my first language, so I’m sorry if I’m adding noise,
but it sounds like some intermixing is going on here.
Oh…
I thought I could with apt since I could install it with apt.
$gpioinfo
gpioinfo shows what is available but I have yet to use GPIO with that specific kernel in Python3.
Seth
P.S. P8_11 and P8_12 are both input and not used. This gives me ideas on if or how to use those specific pins yet I cannot for some reason. I am controlling a driver with STEP and DIR only, i.e. well…along with GND too. I seem to be missing something…anyway. I will keep trying. I will have more time later today.
I am back on kernel 5.10.x in Bookworm along with sysfs
You can certainly install some Python modules with apt. There are usually not the latest version though. You have to be careful mixing apt and pip package if you are not installing into a venv though.
I have noticed this also…
apt and pip modules tend to place their binaries or working directories in separate locations where the files sometimes do not always know what to use or when…
I have installed a venv just in case, i.e. esp. when working with apt and pip on the same system.
Seth
Then it is a python issue, it would not have responded with the pin assignments if that was faulty.
I think for those on 6.1.x kernels, the python3 binding was not ported…
Odd.
Anyway, no issue. I already went back in time to 5.10.x.
Seth
#!/usr/bin/env python
import time
import os
import signal
import sys
# Motor is attached here
# controller = ["P9_11", "P9_13", "P9_15", "P9_17"];
# controller = ["30", "31", "48", "5"]
# controller = ["P9_14", "P9_16", "P9_18", "P9_22"];
controller = ["50", "51", "4", "2"]
states = [[1,0,0,0], [0,1,0,0], [0,0,1,0], [0,0,0,1]]
statesHiTorque = [[1,1,0,0], [0,1,1,0], [0,0,1,1], [1,0,0,1]]
statesHalfStep = [[1,0,0,0], [1,1,0,0], [0,1,0,0], [0,1,1,0],
[0,0,1,0], [0,0,1,1], [0,0,0,1], [1,0,0,1]]
curState = 0 # Current state
ms = 100 # Time between steps, in ms
maxStep = 22 # Number of steps to turn before turning around
minStep = 0 # minimum step to turn back around on
CW = 1 # Clockwise
CCW = -1
pos = 0 # current position and direction
direction = CW
GPIOPATH="/sys/class/gpio"
def signal_handler(sig, frame):
print('Got SIGINT, turning motor off')
for i in range(len(controller)) :
f = open(GPIOPATH+"/gpio"+controller[i]+"/value", "w")
f.write('0')
f.close()
sys.exit(0)
signal.signal(signal.SIGINT, signal_handler)
print('Hit ^C to stop')
def move():
global pos
global direction
global minStep
global maxStep
pos += direction
print("pos: " + str(pos))
# Switch directions if at end.
if (pos >= maxStep or pos <= minStep) :
direction *= -1
rotate(direction)
# This is the general rotate
def rotate(direction) :
global curState
global states
# print("rotate(%d)", direction);
# Rotate the state according to the direction of rotation
curState += direction
if(curState >= len(states)) :
curState = 0;
elif(curState<0) :
curState = len(states)-1
updateState(states[curState])
# Write the current input state to the controller
def updateState(state) :
global controller
print(state)
for i in range(len(controller)) :
f = open(GPIOPATH+"/gpio"+controller[i]+"/value", "w")
f.write(str(state[i]))
f.close()
# Initialize motor control pins to be OUTPUTs
for i in range(len(controller)) :
# Make sure pin is exported
if (not os.path.exists(GPIOPATH+"/gpio"+controller[i])):
f = open(GPIOPATH+"/export", "w")
f.write(pin)
f.close()
# Make it an output pin
f = open(GPIOPATH+"/gpio"+controller[i]+"/direction", "w")
f.write("out")
f.close()
# Put the motor into a known state
updateState(states[0])
rotate(direction)
# Rotate
while True:
move()
time.sleep(ms/1000)
This is some source from the docs.beagleboard.org pages that I found for a L298 driver. I switched things up a bit and made the source run…
To my surprise, I got it to work but nothing happened. I get it. Some Python3 source in the land of Debian these days.
Too many apt styled library reckonings. Anyway, thank you for trying to make me understand.
Seth
I think you might be closer than you think…
for i in range(len(controller)) :
# Make sure pin is exported
if (not os.path.exists(GPIOPATH+"/gpio"+controller[i])):
f = open(GPIOPATH+"/export", "w")
f.write(pin)
What is the pin variable equal to?
Should that not be i instead?
On my BBGW, I can do:
echo 53 > /sys/class/gpio/export
echo out > /sys/class/gpio/gpio53/direction
echo 1 > /sys/class/gpio/gpio53/value
echo 0 > /sys/class/gpio/gpio53/value
to wiggle the USR0 led.
Just make sure to do a
echo none > /sys/class/leds/beaglebone\:green\:usr0/trigger
in case the kernel is controlling the leds in the first place… 
Note! Your leds might be named differently, so adapt the path.
with the sysfs GPIO pins, I am NOT supposed to export the pins in question. It makes them remove themselves somehow.
Seth
P.S. For some reason, my other source I am using is a bit troubled too. I tried with sysfs and gpiod. Neither make this motor move. I probably need a decent PSU for the BBBW. Hmm. That may be it. I need to check…
I will return service once I get it hooked up and tested.
You’re right; if the gpio is already exported, you’ll get a write error: Operation not permitted,
but the line
if (not os.path.exists(GPIOPATH+"/gpio"+controller[i])):
is protecting against this condition, so I’m still pretty sure that you want to use
the i varlable instead of pin.
You didn’t mention if you tried to wiggle the USR0 led, so if you didn’t, could you please try?
While you’re at it, could you include the output of:
ls /sys/class/gpio
ls /sys/class/leds
and
gpioinfo
It’ll give a clearer picture of what you’re dealing with…
Sure,
I will get to the ls commands soon and the gpioinfo command too.
Please be patient.
Seth
ls /sys/class/leds
beaglebone:green:usr0 beaglebone:green:usr1 beaglebone:green:usr2
beaglebone:green:usr3 mmc0:: mmc2::
and… ls /sys/class/gpio
export gpio113 gpio13 gpio23 gpio32 gpio38 gpio47 gpio60 gpio67 gpio72 gpio78 gpio87 gpiochip64
gpio10 gpio114 gpio14 gpio26 gpio33 gpio39 gpio48 gpio61 gpio68 gpio73 gpio79 gpio88 gpiochip96
gpio11 gpio115 gpio15 gpio27 gpio34 gpio4 gpio49 gpio62 gpio69 gpio74 gpio8 gpio89 unexport
gpio110 gpio116 gpio2 gpio3 gpio35 gpio44 gpio5 gpio63 gpio7 gpio75 gpio80 gpio9
gpio111 gpio117 gpio20 gpio30 gpio36 gpio45 gpio50 gpio65 gpio70 gpio76 gpio81 gpiochip0
gpio112 gpio12 gpio22 gpio31 gpio37 gpio46 gpio51 gpio66 gpio71 gpio77 gpio86 gpiochip32
and gpioinfo
gpiochip0 - 32 lines:
line 0: "[mdio_data]" unused input active-high
line 1: "[mdio_clk]" unused input active-high
line 2: "P9_22 [spi0_sclk]" "P9_22" input active-high [used]
line 3: "P9_21 [spi0_d0]" "P9_21" input active-high [used]
line 4: "P9_18 [spi0_d1]" "P9_18" input active-high [used]
line 5: "P9_17 [spi0_cs0]" "P9_17" input active-high [used]
line 6: "[mmc0_cd]" "cd" input active-low [used]
line 7: "P8_42A [ecappwm0]" "P9_42" input active-high [used]
line 8: "P8_35 [lcd d12]" "P8_35" input active-high [used]
line 9: "P8_33 [lcd d13]" "P8_33" input active-high [used]
line 10: "P8_31 [lcd d14]" "P8_31" input active-high [used]
line 11: "P8_32 [lcd d15]" "P8_32" input active-high [used]
line 12: "P9_20 [i2c2_sda]" "P9_20" input active-high [used]
line 13: "P9_19 [i2c2_scl]" "P9_19" input active-high [used]
line 14: "P9_26 [uart1_rxd]" "P9_26" input active-high [used]
line 15: "P9_24 [uart1_txd]" "P9_24" input active-high [used]
line 16: "[rmii1_txd3]" unused input active-high
line 17: "[rmii1_txd2]" unused input active-high
line 18: "[usb0_drvvbus]" unused input active-high
line 19: "[hdmi cec]" unused input active-high
line 20: "P9_41B" "P9_41" input active-high [used]
line 21: "[rmii1_txd1]" unused input active-high
line 22: "P8_19 [ehrpwm2a]" "P8_19" input active-high [used]
line 23: "P8_13 [ehrpwm2b]" "P8_13" input active-high [used]
line 24: "NC" unused input active-high
line 25: "NC" unused input active-high
line 26: "P8_14" "P8_14" input active-high [used]
line 27: "P8_17" "P8_17" input active-high [used]
line 28: "[rmii1_txd0]" "enable" output active-high [used]
line 29: "[rmii1_refclk]" "interrupt" input active-high [used]
line 30: "P9_11 [uart4_rxd]" "P9_11" input active-high [used]
line 31: "P9_13 [uart4_txd]" "P9_13" input active-high [used]
gpiochip1 - 32 lines:
line 0: "P8_25 [mmc1_dat0]" "P8_25" input active-high [used]
line 1: "[mmc1_dat1]" "P8_24" input active-high [used]
line 2: "P8_5 [mmc1_dat2]" "P8_05" input active-high [used]
line 3: "P8_6 [mmc1_dat3]" "P8_06" input active-high [used]
line 4: "P8_23 [mmc1_dat4]" "P8_23" input active-high [used]
line 5: "P8_22 [mmc1_dat5]" "P8_22" input active-high [used]
line 6: "P8_3 [mmc1_dat6]" "P8_03" input active-high [used]
line 7: "P8_4 [mmc1_dat7]" "P8_04" input active-high [used]
line 8: "NC" unused input active-high
line 9: "NC" unused input active-high
line 10: "NC" unused input active-high
line 11: "NC" unused input active-high
line 12: "P8_12" "P8_12" input active-high [used]
line 13: "P8_11" "P8_11" input active-high [used]
line 14: "P8_16" "P8_16" input active-high [used]
line 15: "P8_15" "P8_15" input active-high [used]
line 16: "P9_15A" "P9_15" input active-high [used]
line 17: "P9_23" "P9_23" input active-high [used]
line 18: "P9_14 [ehrpwm1a]" "P9_14" input active-high [used]
line 19: "P9_16 [ehrpwm1b]" "P9_16" input active-high [used]
line 20: "[emmc rst]" unused input active-high
line 21: "[usr0 led]" "beaglebone:green:usr0" output active-high [used]
line 22: "[usr1 led]" "beaglebone:green:usr1" output active-high [used]
line 23: "[usr2 led]" "beaglebone:green:usr2" output active-high [used]
line 24: "[usr3 led]" "beaglebone:green:usr3" output active-high [used]
line 25: "[hdmi irq]" unused input active-high
line 26: "[usb vbus oc]" unused input active-high
line 27: "[hdmi audio]" unused input active-high
line 28: "P9_12" "P9_12" input active-high [used]
line 29: "P8_26" "P8_26" input active-high [used]
line 30: "P8_21 [emmc]" "P8_21" input active-high [used]
line 31: "P8_20 [emmc]" "P8_20" input active-high [used]
gpiochip2 - 32 lines:
line 0: "P9_15B" unused input active-high
line 1: "P8_18" "P8_18" input active-high [used]
line 2: "P8_7" "P8_07" input active-high [used]
line 3: "P8_8" "P8_08" input active-high [used]
line 4: "P8_10" "P8_10" input active-high [used]
line 5: "P8_9" "P8_09" input active-high [used]
line 6: "P8_45 [hdmi]" "P8_45" input active-high [used]
line 7: "P8_46 [hdmi]" "P8_46" input active-high [used]
line 8: "P8_43 [hdmi]" "P8_43" input active-high [used]
line 9: "P8_44 [hdmi]" "P8_44" input active-high [used]
line 10: "P8_41 [hdmi]" "P8_41" input active-high [used]
line 11: "P8_42 [hdmi]" "P8_42" input active-high [used]
line 12: "P8_39 [hdmi]" "P8_39" input active-high [used]
line 13: "P8_40 [hdmi]" "P8_40" input active-high [used]
line 14: "P8_37 [hdmi]" "P8_37" input active-high [used]
line 15: "P8_38 [hdmi]" "P8_38" input active-high [used]
line 16: "P8_36 [hdmi]" "P8_36" input active-high [used]
line 17: "P8_34 [hdmi]" "P8_34" input active-high [used]
line 18: "[rmii1_rxd3]" unused input active-high
line 19: "[rmii1_rxd2]" unused input active-high
line 20: "[rmii1_rxd1]" unused input active-high
line 21: "[rmii1_rxd0]" unused input active-high
line 22: "P8_27 [hdmi]" "P8_27" input active-high [used]
line 23: "P8_29 [hdmi]" "P8_29" input active-high [used]
line 24: "P8_28 [hdmi]" "P8_28" input active-high [used]
line 25: "P8_30 [hdmi]" "P8_30" input active-high [used]
line 26: "[mmc0_dat3]" unused input active-high
line 27: "[mmc0_dat2]" unused input active-high
line 28: "[mmc0_dat1]" unused input active-high
line 29: "[mmc0_dat0]" unused input active-high
line 30: "[mmc0_clk]" unused input active-high
line 31: "[mmc0_cmd]" unused input active-high
gpiochip3 - 32 lines:
line 0: "[mii col]" unused input active-high
line 1: "[mii crs]" unused input active-high
line 2: "[mii rx err]" unused input active-high
line 3: "[mii tx en]" unused input active-high
line 4: "[mii rx dv]" unused input active-high
line 5: "[i2c0 sda]" unused input active-high
line 6: "[i2c0 scl]" unused input active-high
line 7: "[jtag emu0]" unused input active-high
line 8: "[jtag emu1]" unused input active-high
line 9: "[mii tx clk]" "fixedregulator@2" output active-high [used]
line 10: "[mii rx clk]" "LS_BUF_EN" output active-high [used]
line 11: "NC" unused input active-high
line 12: "NC" unused input active-high
line 13: "[usb vbus en]" unused input active-high
line 14: "P9_31 [spi1_sclk]" "P9_31" input active-high [used]
line 15: "P9_29 [spi1_d0]" "P9_29" input active-high [used]
line 16: "P9_30 [spi1_d1]" "P9_30" input active-high [used]
line 17: "P9_28 [spi1_cs0]" "P9_28" input active-high [used]
line 18: "P9_42B [ecappwm0]" "P9_92" input active-high [used]
line 19: "P9_27" "P9_27" input active-high [used]
line 20: "P9_41A" "P9_91" input active-high [used]
line 21: "P9_25" "P9_25" input active-high [used]
line 22: "NC" unused input active-high
line 23: "NC" unused input active-high
line 24: "NC" unused input active-high
line 25: "NC" unused input active-high
line 26: "NC" unused input active-high
line 27: "NC" unused input active-high
line 28: "NC" unused input active-high
line 29: "NC" unused input active-high
line 30: "NC" unused input active-high
line 31: "NC" unused input active-high
So, currently, I am using P8_11, P8_12, and P9_11.
P8_11 is GPIO45
P8_12 is GPIO44
and…
P9_11 is GPIO30
Also…something I noticed. When I use gpiod, some of my used pins, GPIO30 in this case, are removed for when I use sysfs again.
Seth
P.S. I understand that this is supposed to be this way but I just wanted to inform you.
Yea, I don’t want to be a spoilsport but all the pins you have in mind are already claimed by
some device in Linux; note the little [used] tag at the end of the line.
That means that they have most likely been pin-muxed to one of the built-in hardware devices
inside the am335x processor and unavailable to the sysfs files.
You will have to study the schematic and the device-tree to see what pins can safely be reclaimed.
Derek Molloy has written extensively about this exact topic and can save you hours of heartburn.
The reason I wanted you to play with gpio 53 to 56 was because they are safe to repurpose
for a quick-n-dirty-lets-see-if-this-works kind of scenario.
You just need to do a
echo none > /sys/class/leds/beaglebone\:green\:usr[0-3]/trigger
to get the Linux led driver out of your hair.
If you change your program to use 53 to 56, you might even see the leds flash if you tune
up the ms variable to say, 500.
Thank you,
I will see.
Seth
Perhaps this pinmuxing link could be of some interest to you as well…
I can’t vouch for the applicability, but it sounded like on topic.