otg service needs to run before serial-getty

README.md

@@ -8,6 +8,7 @@ Scripts and documentation for setting up a Raspberry Pi (Zero W 1 or 2) for use
 1. [Solder the GPIO header pins](solder-gpio.md)
 1. [Gadget Mode to setup a serial connection over USB](gadget.md)
 1. [Marcel's script on github to show the IP address on the OLED screen](https://github.com/mkyas/cpsy-display-ip)
+1. Install Blinka by following the guide [CircuitPython Libraries on Linux and Raspberry Pi](https://learn.adafruit.com/circuitpython-on-raspberrypi-linux/installing-circuitpython-on-raspberry-pi)]
 
 ## RU student-only guides at ROB-IOT
 - [Starting on Raspberry Pi Zero](https://reykjavik.instructure.com/courses/6589/pages/starting-on-raspberry-pi-zero-w)
@@ -30,6 +31,7 @@ Scripts and documentation for setting up a Raspberry Pi (Zero W 1 or 2) for use
 
 ## TODO
 - Finding the Pi using `nmap` or `arp`
+- Create a interface HAT that makes it easy to attach to a digital analyzer (v207) and an Analog Discovery
 # Some Tricks
 
 Here is a page of tricks we have discovered that may involve advanced techniques.

Scripts/serial-ether-gadget.service

@@ -1,6 +1,7 @@
 [Unit]
 Description=Serial and Ethernet over OTG USB
-After=systemd-user-sessions.service
+#After=systemd-user-sessions.service
+Before=serial-getty@ttyGS0.service
 [Service]
 ExecStart=/root/rover-pi/Scripts/gadget.sh
 [Install]

bluetooth.md

@@ -0,0 +1,79 @@
+# Bluetooth on the Raspberry Pi Zero W (1 or 2)
+The Zero W series has Bluetooth capability because of the Wifi chip on the board.
+**Warning:  This is a work in progress!!!**
+
+# Reference
+- "Exploring Raspberry Pi" by Derek Molloy pg 537-544
+- [Connecting to a Headless Raspberry Pi using Bluetooth](https://medium.com/@tomw3115/connect-to-a-headless-raspberry-pi-using-bluetooth-0e61c05e1b68)
+- https://github.com/sorah/bluetooth-getty
+- [Use dbus insteadd of sdptool](https://linuxvox.com/blog/bluez-adding-services-attributes-and-profiles-without-sdptool-command/)
+
+# Getting Bluetooth working
+1. Login to the pi via a USB-serial port or monitor-keyboard-mouse.  Configuring bluetooth can sometimes kick you off the wifi.
+1. Tell `rfkill` to unblock bluetooth.  Perhaps this is a security thing?
+```
+sudo rfkill unblock bluetooth
+```
+1. Restart the bluetooth service and check it's status
+```
+sudo systemctl restart bluetooth
+sudo systemctl status bluetooth
+```
+1. Figure out the address using `hcitool`
+```
+hcitool dev
+```
+1. If you have a laptop set to be discoverable, you can check if bluetooth is working
+```
+hcitool scan
+```
+1. You can then query that device for what services it offers
+```
+sdptool browse ADDRESS
+```
+1. Now we want to make the Pi discoverable to our phone, tablet, or laptop
+```
+sudo hciconfig hci0 piscan
+sudo hciconfig hci name RaspberryPi
+```
+1. A Serial Port Profile(SPP) is needed for our serial port
+```
+sudo sdptool add SP
+```
+1. For some reason, we have to put the bluetooth daemon in compatibility mode.  (True as of 2016-2026 --foley).  Find the line with `ExecStart` and put `--compat` at the end
+```
+sudo nano /lib/systemd/system/bluetooth.service
+```
+1. Test the SPP is setup
+
+```
+sudo sdptool browse local
+```
+1. Time to pair it with a device
+```
+sudo bluetoothctl
+discoverable on
+agent on
+pairable on 
+scan on
+```
+and once you have paired it
+```
+discoverable off
+exit
+```
+
+1. If this works, you can install the `bluetooth.services` and `rfcomm.service` files to automate some of this setup.
+```
+sudo cp bluetooth.service /etc/systemd/system/bluetooth.target.wants/.
+sudo cp rfcomm.service /etc/systemd/system/.
+sudo systemctl daemon-reload
+sudo systemctl enable rfcomm
+sudo reboot
+
+```
+
+
+
+# Discussion
+Apparently Bluez's `sdptool` is now depricated and they are telling people to use this new GATT via `busctl` or `dbus-send`. [linuxvox article on depricated sdptool](https://linuxvox.com/blog/bluez-adding-services-attributes-and-profiles-without-sdptool-command/)

lgpio/motor-test.py

@@ -0,0 +1,34 @@
+#!/usr/bin/python
+# This test assumes you are trying to control a motor through a DRV8833 motor
+# controller chip.  This general approach should work for other motors as well.
+import lgpio
+import time
+
+# pin assignments
+gpio_pwm = 18  #MOTA1
+gpio_reverse = 16 #MOTA2
+gpio_notsleep = 24 #MSLEEP
+# parameters
+pwm_freq = 1000
+
+
+h = lgpio.gpiochip_open(0)
+try:
+    lgpio.gpio_claim_output(h, gpio_reverse)
+    lgpio.gpio_claim_output(h, gpio_notsleep)
+    lgpio.gpio_write(h, gpio_reverse, 0)   # low on reverse pin to turn off h-bridge MOTA2
+    lgpio.gpio_write(h, gpio_notsleep, 1)   # high on /sleep to enable both h-bridges
+    
+    while True:
+        for pwm_level in range(0,100):
+            lgpio.tx_pwm(h, gpio_pwm, pwm_freq, pwm_level)
+            pwm_level += 10
+            time.sleep(0.05)
+        for pwm_level in range(100,0,-1):
+            lgpio.tx_pwm(h, gpio_pwm, pwm_freq, pwm_level)
+            pwm_level += 10
+            time.sleep(0.05)
+
+finally:
+    lgpio.gpio_write(h, gpio_notsleep, 1)   # high on /sleep to disable    
+    lgpio.gpiochip_close(h)          # Always close!

lgpio/pwm-test.py

@@ -5,21 +5,21 @@ import time
 
 # Open GPIO chip (0 = /dev/gpiochip0, on Pi 5 gpiochip4 also possible)
 h = lgpio.gpiochip_open(0)
-
+# Hardware PWM on GPIO18 (pin 12) must be PWM-capable
+pwm_pin = 18
+pwm_freq = 1000
 try:
-    lgpio.gpio_claim_output(h, 16)   # GPIO16 as output (MOTA2)
-    lgpio.gpio_write(h, 16, 0)   # LOW
+    while True:
+        for pwm_level in range(0,100):
+            lgpio.tx_pwm(h, pwm_pin, pwm_freq, pwm_level)
+            pwm_level += 10
+            time.sleep(0.05)
+        for pwm_level in range(100,0,-1):
+            lgpio.tx_pwm(h, pwm_pin, pwm_freq, pwm_level)
+            pwm_level += 10
+            time.sleep(0.05)
 
-    # Hardware PWM on GPIO18 (pin 12) must be PWM-capable
-    # Frequency: 1000 Hz, duty cycle: 50%
-    lgpio.tx_pwm(h, 18, 1000, 50)
-    time.sleep(2)
-
-    # Reduce duty cycle to 20%
-    lgpio.tx_pwm(h, 18, 1000, 20)
-    time.sleep(2)
-
-    lgpio.tx_pwm(h, 18, 0, 0)   # Stop PWM
             
 finally:
+    lgpio.tx_pwm(h, pwm_pin, 0, 0)   # Stop PWM
     lgpio.gpiochip_close(h)          # Always close!

pwm.md

@@ -4,15 +4,20 @@ The Raspberry Pi zero (1 and 2) have 2 PWM peripherals, allowing you to pulse pi
 
 
 # References
+- [CircuitPython Libraries on Linux and Raspberry Pi](https://learn.adafruit.com/circuitpython-on-raspberrypi-linux/installing-circuitpython-on-raspberry-pi)
 - [Raspberry Pi Official Overlays information (github)](https://github.com/raspberrypi/firmware/blob/master/boot/overlays/README)
     - Line 4235 starts the description of the "pwm" overlay configuration
 - [Adding Basic Audio Ouput to Raspberry Pi Zero](https://learn.adafruit.com/adding-basic-audio-ouput-to-raspberry-pi-zero/pi-zero-pwm-audio)
+- [CircuitPython pwmio documentation](https://docs.circuitpython.org/en/latest/shared-bindings/pwmio/index.html)
+
 
 # Important Points
 1. The `gpio` program is no longer available.  It has been replaced with `pinctrl` which works a little differently.
+1. The Blinka/CircuitPython interface uses `lgpio` to do hardware PWM on the pins.  This requires the `pwm-2chan` overlay to be setup correctly, which it's documented procedure does.  Details on relevant pins on line 4267 of the [overleays README](https://github.com/raspberrypi/firmware/blob/master/boot/overlays/README)
 
 # Discussion
 
+
 My raspberry pi zero W 2 wasn't working reliably with the PWM.
 
 The `gpio` command has been depricated and is now replaced by the `pinctrl` commend.  Running it did not list any PWM0 on any of the pins, which was concerning.