Raspjamming OS for Banana Pi M2 Zero

Decription

Raspjamming OS is a Raspberry Pi OS (32-bit) Lite based linux distribution for use at Raspberry Pi jams. Especially for use with Raspjamming-Event, organised from the GC2 - Grazer Computer Club.

Main features

see releases

Download

Go to releases to download compressed image and use etcher for Linux or Rufus for Windows to write it to sd card. After first boot expand filesystem with 'sudo raspi-config' (7 Advance Options -> A1 Expand Filesystem).

Banana-Pi-M2-Zero

Repository contains Raspjamming OS files for supporting Banana Pi M2 Zero (BPI-M2 Zero) Special thanks to https://github.com/avafinger/bananapi-zero-ubuntu-base-minimal for providing the first kernel data
Special thanks to https://www.armbian.com for providing Kernel 4 build system

Specification

• Allwinner H2+ SoC (4x Cortex-A7)
• 512 MB DDR3
• Wifi 2,4 GHz, 802.11b/g/n single-band radio (65 Mps)
• Bluetooth 4.0 (BLE)
• 40 Pin GPIO + UART

Datasheets and schematic

BPi-M2-Zero schematic
Allwinner H2+
AP6212 WiFi+BT

Links

U-Boot
U-Boot: Quick reference
Kernel arguments
Getting Started with M2 Zero

GPIO - numbers (WiringPi)

Project goal

• Get as near as possible to Raspbbery Pi Zero W (replacement)
• 100% GPIO compatible to Raspberry Pi
• Support GC2-xHAT
• Support USB-HAT

unlikely/impossible:

• Hardware PWM
• Audio out via GPIO-PWM
• I2S
• Camera
• Support Pi-XO, xGame0-HAT

Status Raspjamming OS

Kernel: 4.19.129 / 4.19.12
ARM-CPU clock speed: 120 - 1008 MHz
Active cores: 2
GPU Memory: 16 MB
Memory: 496 MB

Features disabled:

• Ethernet (eth0)
• 2-Cores
• SPI1
• UART2 (GPIO)

To do list:

• USB ethernet gadget: OK
• USB client: OK
• WiFi: OK
• ACT-LED: OK
• Shutdown button (PL3 - Pin355): NOK (pin ist not set correctly to input after boot, maybe edge mode? active low!)
• GPIO Librarys (tools)
  • WiringPi: OK
  • WiringPi - ISR: OK
  • C# - WiringPi wrapper: OK
  • RPi.GPIO (python2): untested
  • RPi.GPIO (python3): OK
  • RPi.GPIO (python3) - Event: OK
  • gpiozero (python3): OK
  • libgpiod: untested
• Remove UART2: OK
• Debug UART (UART0): OK (visible as UART2, Uboot Messages, Console)
• BT: unknown
• BT UART: unknown (visible as UART1)
• GPIO
  • GPIO RS232 (UART3): OK (visible as UART0, Kernel Messages, Console)
  • GPIO SPI0 - CS0 & CS1: OK
  • GPIO I2C-1 (400 kHz): OK
  • GPIO I/O: OK (WiringPi 2.60.200413)
  • GPIO init: NOK (GPIOs not set correctly to input mode after boot)
  • GPIO pullup: NOK (Raspberry Pi, GPIO00-GPIO07 pull-up is activated default)
  • GPIO Event/ISR: OK
• GC2xHAT:
  • HC-SR04 - C: OK
  • HC-SR04 - C#: NOK (invalid values)
  • HC-SR04 - gpiozero(Python3): NOK (event missing)
  • 3xSwitch: OK
  • LEDs: OK
  • TM1637: OK (some errors)
  • Power 3.3V: OK (but default on, rpi default off)
  • DHT - C: NOK
  • DHT - C#: OK
  • ATMEGA: NOK (resetpin must be set to 2, but still reading device id wrong - spi error?)
  • ESP01: ?
  • AM2320.py: NOK ('board not supported' error)
  • HAT EEPROM: NOK (manuel implementation needed)
• 4K Console: OK
• 4K X-Windows: OK (CPU overheating >77°C at idle, unuseable)
• Force HDMI 720p Resolution: NOK
• Device-Tree at shell: NOK (new Kernel needed)
• User GPIO access: NOK (new Kernel needed)
• Application tests:
  • mplayer: OK
  • emulator Gamebatte: OK
  • emulator PicoDrive: OK
  • PICO-8: OK
  • armbianmonitor: OK

Pin access via sysfs

https://linux-sunxi.org/GPIO

(position of letter in alphabet - 1) * 32 + pin number
PL3 = (12-1) *32 + 3 = 355

echo 355 > /sys/class/gpio/export
echo "in" > /sys/class/gpio/gpio355/direction
cat /sys/class/gpio/gpio355/value

strange behavior (sysfs and wringpi)

echo 0 > /sys/class/gpio/export
echo "in" > /sys/class/gpio/gpio0/direction changes wiringpi GPIO Mode to 'IN'
cat /sys/class/gpio/gpio0/value changes wiringpi GPIO Mode to 'ALT2'
It looks like wiringPi can not read wenn Mode 'ALT2' is active (always zero).
This creates following error: If event/ISR is activated on GPIO, reading the input via memory map is not possible anymore.
The problem was solved in wiringPi and RPi.GPIO by reading via /sys/class/gpio/gpioX/value in that case.

Measurements

Consumption & temperature (22 °C ambient):

Banana Pi M2 Zero

Console/no Video:
Idle : 140 mA (47 °C)
1-core (stress): 260 mA (60 °C)
2-core (stress): 320 mA (70 °C, max. CPU temperature, CPU freq. adjustment active 816-1008 MHz)
4K X-Windows:
Idle : 350 mA (77 °C, CPU overheated, CPU freq. adjustment active 120 MHz)

Raspberry Pi Zero W

Idle : 110 mA (38 °C)
1-core (stress): 190 mA (45 °C)

CPU Performance (nBench mean value):

nbench.txt Banana Pi M2 Zero

1008 MHz: 5,868 (see details)
960 MHz: 5,602
816 MHz: 4,762

Raspberry Pi

Pi 2 , 900 MHz: 5,2
Pi Zero, 1150 MHz: 4,662
Pi Zero, 1000 MHz: 4,010

for more benchmark results please see github Benchmark repro

Read HAT

i2cdump -y 0 0x50 c  
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f    0123456789abcdef  
00: 52 2d 50 69 01 00 02 00 8c 00 00 00 01 00 00 00    R-Pi?.?.?...?...  
10: 50 00 00 00 01 dc 73 71 97 89 f3 91 3a 40 5f 8c    P...??sq????:@_?  
20: 00 75 ec 91 20 6c 00 01 1e 1a 47 72 61 7a 65 72    .u?? l.???Grazer  
30: 20 43 6f 6d 70 75 74 65 72 20 43 6c 75 62 20 28     Computer Club (  
40: 41 75 73 74 72 69 61 29 47 43 32 2d 78 48 41 54    Austria)GC2-xHAT  
50: 20 28 52 61 73 70 6a 61 6d 6d 69 6e 67 20 48 41     (Raspjamming HA  
60: 54 29 de f1 02 00 01 00 20 00 00 00 00 00 00 00    T)???.?. .......  
70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................  
80: 00 00 00 00 00 00 00 00 00 00 ed 6e 00 00 00 00    ..........?n....  

0x28 ... length organisation
0x29 ... length product
0x2A ... organisation & product