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RE: BeagleBone AI Survival Guide V3.18: PWM, I2C, Analog/Digital Read/Write, Vision AI, Video Text Overlays, Audio, & Hardware

persyn — Mon, 20 Sep 2021 21:31:28 GMT

Hello,

I am trying to control a robotic arm (4 servo's) with the beaglebone ai. I was able to generate a PWM signal on P9_14 trough the example pwmout.c but need 4 in total. I tried to control /sys/class/pwm/pwm-0:1 instead of /sys/class/pwm/pwm-0:0 and expected to be able to PWM P9_16 but this doesn't work. Can someone help me how to control multiple (4) PWM signals with the beaglebone ai?

RE: BeagleBone AI Survival Guide V3.18: PWM, I2C, Analog/Digital Read/Write, Vision AI, Video Text Overlays, Audio, & Hardware

themysticturtle — Tue, 06 Jul 2021 17:01:02 GMT

Hello! I have followed the tutorial (as it sits on 7/6/2021.. wow. are we really that far along in 2021?) to set up the BBAI. including the pinmuxing.

Now, i can see the data stream running analongInSync.js or analogInCallBack.js using a simple phototransistor going from one of the VDD3v3B slots to the positive side, and taking my readings from the negative side hooked to P9.36 analog input. with the v- side of phototransistor also pulled to ground via 10kohm resistor. (i get good results in the data feed on my cloud9 ide console, as well as when i view this output directly with my siglent oscilloscope)

However, when i attempt to do the analogInOut.js. even after verifying my p9.14 and p9.16 are correctly muxed as PWM outputs with the show-pins command in console.

"

P9.14 107 fast down 10 pwm 2 A pwm@48442200 (ehrpwm2)

P9.16 108 fast down 10 pwm 2 B pwm@48442200 (ehrpwm2)"

I get an interesting error. " error: error updating PWM freq and value: undefined, Error: ENOENT: no such file or directory, open 'undefined/period' "

Here is the code directly from the file i am attempting to run.

""
#!/usr/bin/env node

////////////////////////////////////////

// analogInOut.js

// Reads analog in on P9_36 and adjusts the PWM on P9_14.

// Wiring: Attach the outer pins on a variable resistor to P9_32 and P9_34.

// Attach the wiper (middle pin) of the resistor to P9_36.

// P9_14 connects to the plus lead of an LED. The negative lead of the

// LED goes to a 220 Ohm resistor. The other lead of the resistor goes

// to ground.

// Setup:

// See:

////////////////////////////////////////

const b = require('bonescript');

const inputPin = "A5";

const outputPin = "P9_14";

console.log('Hit ^C to stop');

b.pinMode(outputPin, b.ANALOG_OUTPUT);

setTimeout(loop, 400); // work-around to wait for PWM permissions

function loop() {

var value = b.analogRead(inputPin);

process.stdout.write(inputPin + '-->' + outputPin + ': ' + (value*100).toFixed(1) + '% \r');

b.analogWrite(outputPin, value);

setTimeout(loop, 10);

}

// Bone | Pocket | AIN

// ----- | ------ | ---

// P9_39 | P1_19 | A0

// P9_40 | P1_21 | A1

// P9_37 | P1_23 | A2

// P9_38 | P1_25 | A3

// P9_33 | P1_27 | A4

// P9_36 | P2_35 | A5

// P9_35 | P1_02 | A6

""

Any ideas why this is occurring?

I am totally new to coding, and trying to figure this out. As far as i can tell. what is going on in this program is it calls up the bonescript. I am not entirely sure what bonescript is, but i imagine it allows everything on the beaglebone board to communicate with each other and route signals properly.

then it sets a constant of A5. or P9-36 as an input pin.

It also sets P9-14 PWM pin as an output pin constant.

It sets the pin mode of our constant output pin. to analog_output.

i am not sure what the set timeout does, but i imagine it delays the program erroring out to hopefully wait for the PWM permissions to activate (which i do not think mine are?)

then it runs a loop of variable "value" = the analog read of our constant "input pin"

Then the process.stdout.write continually prints the information as the data is being retrieved. then it does inputpin + something + output pin + something + (value variable * 100).toFixed (no idea what that does x 1) + i have no earthly idea.
Then it is supposed to analog write to the output pin, the value it calculated from that formula i do not understand.
I assume the timeout is how long it has to accomplish this before the program errors out of it does not get a result.

Please pardon my ignorance on the programming side of things. I specialize in hardware design. Fixtures/jigs/tools/cnc programing. Industrial manufacturing process optimization. And they also have me build custom automated industrial equipment they can not find for sale out here in the R&D lab.

So far, i have cheated and used an RPI and matlab/simulink/stateflow.

Now, my goal is to be able to run a touch screen based GUI (still with a physical/hard e-stop) to control this BBAI board.
I have QT design studio, open source, and i am trying to learn how to actually code this and link a touch screen GUI to read and control various pins. So it is finally time for me to learn some proper coding. (any advice or suggestions is always greatly appreciated)

The end result of this first project will hopefully be a device to semi automate the process of pressure/water testing on some units we produce. I intend to have a differential pressure sensor sending in an analogue signal to do a PID type control of a blower motor to maintain the set PSF of vacuum or pressure. or follow a program.

While the sensors collect data about temperature/humidity. relative atmospheric pressure vs dynamic test pressure. calculate CFM. and graph these values on some form of chart/report i can export to a local server folder.

My previous contraptions were all button control panel based looking for GPIO inputs to change the machine behavior.

Any insight, recommendations, or help with this would be greatly appreciated. I would be happy to assist you guys with any of your hardware design/cad cam/cnc programming/ pcb design and layout needs in return [View:/resized-image/__size/16x16/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-adca0adf-a42b-4735-886c-6f1abe1a8dfe/contentimage_5F00_2516.png:16:16]

Thank you all very much for your time, and your expertise. And a big shout out to @sean miller for taking the time and effort to put this tutorial together.

RE: BeagleBone AI Survival Guide V3.18: PWM, I2C, Analog/Digital Read/Write, Vision AI, Video Text Overlays, Audio, & Hardware

dianem — Thu, 06 May 2021 16:21:23 GMT

For anyone having trouble with getting the other four analog inputs to work, I have found a solution. After performing the pinmuxing procedure defined above, the file am5729-beagleboneai.dts defines four subdevices under the STMPE811: ADC, touchscreen, GPIO, and PWM. If you want to use all of the pins for ADC, you can comment out the other three subdevices from that section to allow the STMPE811 pins to be set up as ADC. After changing am5729-beagleboneai.dts you will have to re-make the .dtb, copy it over, and reboot before the change will take effect.

There may be other ways to enable the ADC pins (maybe the order of the subdevice definition matters?), but this worked in my situation.

RE: Vector Display GPU Project

thehermit — Sat, 27 Feb 2021 06:57:45 GMT

OMG!!! Ended up here after watching your Music Player w/controls video on YT. Can't believe what I've just seen.

In 1978, I was doing Laserium shows in London, until I went freelance. Throughout the 1980's, I was developing laser projection systems for exhibitions and touring w/bands. My forte was developing the projection systems and shows, while my partner(s) did the analog, 6502, or 8088 electronics for the control desk.

Initially, we used crude analog quadrature oscillators w/preamp mixers. Then, we wire wrapped 8 bit digital boards, etc. before progressing on to acid etched PCBs. Back then, I was dreaming of animating line graphics via interpolation between sequences, just as you have demonstrated.

Now, I'm retired and becoming a maker, seriously considering building a vector system with some Teensy MCU quad oscillators, inexpensive RGB diode lasers, and an x/y scanning head. With today's prices and technology, a full color, single head laser projector could be built for <$1000 instead of ~$25,000 back in the day.

Sure wish I had your vector program when I auditioned for Floyd's Division Bell tour back in 1987. Oh well...

Congratulations on your awesome work. I'll be back.

RE: BeagleBone AI Survival Guide V3.18: PWM, I2C, Analog/Digital Read/Write, Vision AI, Video Text Overlays, Audio, & Hardware

lasthorizon — Mon, 17 Aug 2020 15:08:40 GMT

Hi There,

You have in your post a section about installing (making) the tidl_utils library to get access to the tidl model import tool.

I am trying to build this repository but hitting loads of problems (paths not defined, fatal errors in bits/c++config.h etc etc.)

I have a completely clean install of Ubuntu 20.04.

Please can someone detail the exact steps they went through to manage to build tidl_utils, including which OS they are on, which version of the OS and the dependencies?

Many thanks

RE: BeagleBone AI Survival Guide V3.18: PWM, I2C, Analog/Digital Read/Write, Vision AI, Video Text Overlays, Audio, & Hardware

notthetup — Sat, 18 Jul 2020 05:32:22 GMT

As others have said, Thank You for this guide. It's super helpful. I've one question.

Are both pins P9.14 (out-A) and P9.16 (out-B) separately configurable for PWM? What does P9.16 (out-B) get exposed as in Linux?

RE: BeagleBone AI Survival Guide V3.18: PWM, I2C, Analog/Digital Read/Write, Vision AI, Video Text Overlays, Audio, & Hardware

jstumfoll — Sat, 11 Jul 2020 20:17:47 GMT

First off, THANK YOU!!! for this guide, extremely helpful. I was able to get my i2c bus working because of the additions to the device tree you provided. I think I'm starting to get the hang of things. I picked up a robotics cape and I'm slowly getting things to work, all of the code was written for the Beaglebone Black and Blue and has required a number of updates to work. One of the big hurdles I've run into however is the fact that one of the CPU balls wasn't connected in the rev 1A design (https://github.com/beagleboard/beaglebone-ai/issues/22 ). This pin is used to control the direction of one of the motors. Looking through the device tree and possible pin mux modes, it looks like that same pin is connected to a PRU which based on the naming convention I believe to be a general purpose output pin.

DRA7XX_CORE_IOPAD(0x3730, PIN_OUTPUT | MUX_MODE13) /* C17: P9.13a: mcasp3_axr1.pr2_pru0_gpo15 - MDIR1B */ // mode14 isn't available on this pin... Could maybe use mode 13? pr2_pru0_gpo15

Have you tried to do anything with the PRU firmware, i.e. to use a specific pin as a general purpose output? Any references you may be able to point me to? Thanks!

RE: BeagleBone AI Survival Guide V3.18: PWM, I2C, Analog/Digital Read/Write, Vision AI, Video Text Overlays, Audio, & Hardware

mvduin — Fri, 26 Jun 2020 20:44:28 GMT

The ADC inputs on other beaglebones are max 1.8V, but on the BBAI they now accept up to 3.3V. The VDD_ADC pin can provide either 1.8V or 3.3V, but it's configured to provide 1.8V by default to remain backwards-compatible.

RE: BeagleBone AI Survival Guide V3.18: PWM, I2C, Analog/Digital Read/Write, Vision AI, Video Text Overlays, Audio, & Hardware

Jean-Louis — Fri, 26 Jun 2020 20:33:01 GMT

Hello,

excellent document, but there is ambiguity about the name of the power pins on the P9 connector.

On the Beaglebone-AI schematic, pins 5-6 are VDD_CAP_5V and PIN 7-8 are VDD_5V. On the other hand, you noted VDD_5V for pins 5-6 and SYS_5V for pins 7-8, which is a source of error if we refer to the electrical shematic...

RE: BeagleBone AI Survival Guide V3.18: PWM, I2C, Analog/Digital Read/Write, Vision AI, Video Text Overlays, Audio, & Hardware

malavpatel01 — Wed, 03 Jun 2020 11:40:13 GMT

Here i create my custom *.dts file and test all interfaces .if you facing issue regarding any interfaces then please follow below link :

https://github.com/MalavPatel3501/BeagleBone-AI--mpBBAI-IO-Python-Library

In this project you got .dts file and all pin muxing steps. Moreover i puts some example code in this project.

RE: BeagleBone AI Survival Guide V3.18: PWM, I2C, Analog/Digital Read/Write, Vision AI, Video Text Overlays, Audio, & Hardware

silver2row — Tue, 02 Jun 2020 22:52:54 GMT

Hello,

I am trying to run your .c file for working w/ LEDs and PWM for the BBAI. The .c file compiles but I cannot sway that little LED to light up.

...

Um, is there a trick I am not getting? I listened to the .dtb overlay stuff and put it in /boot/uEnv.txt.

Seth

P.S. Please reply if you can find time. By the way, this is a nice write up of the functions and ideas circulating. Thank you.

RE: BeagleBone AI Survival Guide V3.18: PWM, I2C, Analog/Digital Read/Write, Vision AI, Video Text Overlays, Audio, & Hardware

mvduin — Tue, 02 Jun 2020 00:16:49 GMT

Note: the pin IDs shown in the second column are not yet correct as of 10/31/2019. For example, P9.15 is actually 76, not 69.

I'm the author of that spreadsheet. I just double-checked, the value 69 is correct.

From the BeagleBone-AI schematic: P9.15 connects to the net "AG4_GPIO3_12" which connects to VIN1A_D8 (ball AG4) of the AM572x.

From the AM572x TRM: CTRL_CORE_PAD_VIN1A_D8 is at 0x4A003514, which is byte-offset 0x114 into the pinmux array, i.e. index 0x114/4 = 69.

Are you confusing pin index (used for pinmuxing and as way to uniquely identify a pin with a small integer) with gpio numbers?

RE: BeagleBone AI Survival Guide V3.18: PWM, I2C, Analog/Digital Read/Write, Vision AI, Video Text Overlays, Audio, & Hardware

-blacksnow- — Sun, 10 May 2020 13:30:30 GMT

Thank you very much for that guide, it was really helpful!!!

I have question regarding the pinmuxing. Where is that "magic-number" 0x3400 coming from?

Thank you very much

RE: BeagleBone AI Survival Guide V3.18: PWM, I2C, Analog/Digital Read/Write, Vision AI, Video Text Overlays, Audio, & Hardware

mtbeagle — Wed, 29 Apr 2020 20:20:39 GMT

[mention:5517e1b11f91409081f704d23d850071:e9ed411860ed4f2ba0265705b8793d05] The Beaglebone AI does tolerate 3.3V on the ADC Pins. They supply 1.8 for backwards compatibility with older beaglebones.

[View:/resized-image/__size/603x301/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-adca0adf-a42b-4735-886c-6f1abe1a8dfe/contentimage_5F00_191817.png:603:301]

The STMPE811QTR can handle 3.3V on the analog in. Just be sure you don't need backwards compatibility when using 3.3v.

RE: BeagleBone AI Survival Guide V3.18: PWM, I2C, Analog/Digital Read/Write, Vision AI, Video Text Overlays, Audio, & Hardware

sung — Wed, 12 Feb 2020 08:12:44 GMT

BBAI(Beaglebone AI) uart3_txd not working correctly

Hi, ALL

I have a problem with setup UART*.
I'm trying to use pins P9.24(uart10_txd) and P9.26(uart10_rxd) as a UART on a BBAI with Debian 4.14.108-ti-r127

Also I've configured the pins to work as UART by using "sudo /opt/scripts/device/bone/show-pins.pl | sort"
Sadly it does not work properly for Tx pins, from my testing.

I do not know the correct way to set the pins.

*** P9.24(uart10_txd) : not working!
*** P9.26(uart10_rxd) : working.

I've tried other UARTs also but no luck. Any help please ?

----------------------------------------------------------------------------------------------------------------------------------

01) debian@beaglebone:~$ cat /etc/dogtag
BeagleBoard.org Debian Image 2019-12-01

02) debian@beaglebone:~$ sudo /opt/scripts/tools/version.sh
git:/opt/scripts/:[e457c010efc76c4e6fecccb7a5f7ff9b0597c4c0]
model:[BeagleBoard.org_BeagleBone_AI]
dogtag:[BeagleBoard.org Debian Image 2019-12-01]
UBOOT: Booted Device-Tree:[am5729-custom.dts]
kernel:[4.14.108-ti-r127]
nodejs:[v6.17.0]
device-tree-override:[ dtb=am5729-custom.dtb]
/boot/uEnv.txt Settings:
pkg check: to individually upgrade run: [sudo apt install --only-upgrade <pkg>]

03) debian@beaglebone:~$ sudo vi /boot/uEnv.txt
#Docs: http://elinux.org/Beagleboard:U-boot_partitioning_layout_2.0
uname_r=4.14.108-ti-r127

#uuid=
dtb=am5729-custom.dtb

cmdline=coherent_pool=1M net.ifnames=0 rng_core.default_quality=100 quiet

#In the event of edid real failures, uncomment this next line:
#cmdline=coherent_pool=1M net.ifnames=0 rng_core.default_quality=100 quiet video=HDMI-A-1:1024x768@60e

#Use an overlayfs on top of a read-only root filesystem:
#cmdline=coherent_pool=1M net.ifnames=0 rng_core.default_quality=100 quiet overlayroot=tmpfs

##enable x15: eMMC Flasher:
##make sure, these tools are installed: dosfstools rsync
#cmdline=init=/opt/scripts/tools/eMMC/init-eMMC-flasher-v3-no-eeprom.sh

04) debian@beaglebone:/home$ ls /boot/dtbs
4.14.108-ti-r127 am5729-custom.dtb

05) debian@beaglebone:/home$ sudo /opt/scripts/device/bone/show-pins.pl | sort

P9.24                   163 F20 3 fast         uart10_txd       serial@4ae2b000 (uart10)
P9.25                    165 D18 e fast rx down gpio6_17
P9.26a                  162 E21 3 fast rx      uart10_rxd       serial@4ae2b000 (uart10)
P9.26b                   81 AE2 f fast rx      Driver off       serial@4ae2b000 (uart10)

06) am5729-custom.dtb
#include "am5729-beagleboneai.dts"
// make it easy to determine which dtb you're currently running on
// (via /proc/device-tree/chosen/)
/ {
chosen {
base_dtb = "am5729-custom.dts";
base_dtb_timestamp = __TIMESTAMP__;
};
};

// eventually these should be available in a header

//UART1
#define P9_24 (0x3400 + 4 * 163) // uart10 txd (0x368C)
#define P9_26a (0x3400 + 4 * 162) // uart10 rxd (0x3688)
#define P9_26b (0x3400 + 4 * 81) // (shared pin) (0x3544)

// enable uart10 on P9.24 (uart10_txd) + P9.26a (uart10_rxd)
&uart10 {
status = "okay";
// clock-frequency = <400000>;
pinctrl-names = "default";
pinctrl-0 = <&uart10_pins>;
};

&dra7_pmx_core {
uart10_pins: uart10 {
   pinctrl-single,pins = <
     DRA7XX_CORE_IOPAD( P9_24, PIN_OUTPUT    | MUX_MODE3   ) // uart10_txd
     DRA7XX_CORE_IOPAD( P9_26a, PIN_INPUT      | MUX_MODE3 )   // uart10_rxd
     DRA7XX_CORE_IOPAD( P9_26b, PIN_INPUT      | MUX_MODE15 ) // (shared pin)
   >;
};
};

// Here's the obnoxious part: since u-boot doesn't have same pin defaults yet, all pins not
// explicitly setup above should be overridden here.   This will eventually no longer be needed.
&cape_pins_default {
pinctrl-single,pins = <
   ...............................................................................................................................................................
   DRA7XX_CORE_IOPAD( 0x37B4, PIN_INPUT_PULLUP        | MUX_MODE14 )   // P9.23
   // *DRA7XX_CORE_IOPAD( 0x368C, PIN_INPUT_PULLUP     | MUX_MODE14 ) // P9.24   uart10_txd
   DRA7XX_CORE_IOPAD( 0x3694, PIN_INPUT_PULLDOWN   | MUX_MODE14 )   // P9.25
   // *DRA7XX_CORE_IOPAD( 0x3688, PIN_INPUT_PULLUP     | MUX_MODE14 ) // P9.26a uart10_rxd
   // *DRA7XX_CORE_IOPAD( 0x3544, PIN_INPUT                | MUX_MODE14 )      // P9.26b (shared pin)
   ...............................................................................................................................................................
>;
};

Thank you for your time.

Regards,
Sung.