Embedded on Bhuvan Chandra DV

MicroPython running on NXP VF6XX M4 Core

Wed, 19 Jul 2017 08:15:33 +0800

This is an experimental port of MicroPython for NXP VF6XX M4 Core.

Supported features include:

REPL (Python prompt) over UART2
Garbage collector
GPIO, UART support

Build

The toolchain required is the Linaro ARM Embedded toolchain (e.g. 4.9 2015 Q3):

tar xjf ${HOME}/gcc-arm-none-eabi-4_9-2015q3-20150921-linux.tar.bz2
export PATH=$PATH:$HOME/gcc-arm-none-eabi-4_9-2015q3/bin/

Then build:

cd ${HOME}/micropython/vf6xx
make

Booting the M4 Core

Two methods are supported:

1. From U-Boot using bootaux:

Colibri VFxx # fatload mmc 0:1 ${loadaddr} firmware.elf
Colibri VFxx # bootaux ${loadaddr}

2. From Linux using remoteproc:

libsoc Examples on Colibri VF61

Thu, 18 May 2017 11:55:50 +0800

Examples using libsoc on a Colibri VF61 module with an Aster carrier board and Pioneer600 Raspberry Pi expansion cape.

Hardware

Colibri VF61 — Cortex-A5 + Cortex-M4, SODIMM form factor
Aster Carrier Board — Arduino Uno and Raspberry Pi headers
Pioneer600 — RPi expansion cape

Cross-compiling libsoc

Build and install the Yocto SDK first, then:

git clone -b master https://github.com/jackmitch/libsoc.git
cd libsoc
. /usr/local/oecore-x86_64/environment-setup-armv7at2hf-neon-angstrom-linux-gnueabi
autoreconf -i
./configure --host=arm-angstrom-linux-gnueabi \
    --prefix=/usr/local/oecore-x86_64/sysroots/armv7at2hf-neon-angstrom-linux-gnueabi/
make -j$(nproc)
sudo make install

Cross-compiling the examples

git clone https://github.com/bhuvanchandra/libsoc-examples.git
cd libsoc-examples/ssd1306/
MACHINE=colibri-vf make

Copy the binary to the target via SSH and run.

Knuckles Demo Application — DirectFB Fork

Tue, 02 Feb 2016 11:55:43 +0800

Fork of the DirectFB example Knuckles, used in a Linux quick boot demo on Toradex Colibri modules.

Source code

Understanding Linux LCD Display Timings

Tue, 02 Feb 2016 11:55:43 +0800

Mapping LCD/TFT display timings to Linux Kernel data structures

Most LCD/TFT display datasheets provide the following timing information:

Horizontal Back Porch (HBP): Number of pixel clk pulses between HSYNC signal and the first valid pixel data.
Horizontal Front Porch (HFP): Number of pixel clk pulses between the last valid pixel data in the line and the next hsync pulse.
Vertical Back Porch (VBP): Number of lines (HSYNC pulses) from a VSYNC signal to the first valid line.
Vertical Front Porch (VFP): Number of lines (HSYNC pulses) between the last valid line of the frame and the next VSYNC pulse.
VSYNC pulse width: Number of HSYNC pulses when a VSYNC signal is active.
HSYNC pulse width: Number of pixel clk pulses when a HSYNC signal is active.
Active frame width: Horizontal resolution.
Active frame height: Vertical resolution.
Screen width: Active frame width + HBP + HFP
Screen height: Active frame height + VBP + VFP
VSYNC polarity: Value of VSYNC to indicate the start of a new frame (active LOW or HIGH)
HSYNC polarity: Value of HSYNC to indicate the start of a new line (active LOW or HIGH)

Some datasheets provide horizontal and vertical blanking period instead:

Point of Sale Demo with GTK+ and Glade

Tue, 02 Feb 2016 11:55:32 +0800

Point of sale demo application built with GTK+ and Glade, running on Toradex Apalis/Colibri System on Modules.

Source code

Configuring an Embedded Linux Machine as a WiFi Hotspot

Fri, 13 Jun 2014 11:55:43 +0800

How to configure an embedded Linux board (Colibri VF61) as a WiFi access point using hostapd, udhcpd, and iptables.

Test Setup

Colibri VF61 V1.1A
Colibri Evaluation Board V3.1a / Iris V1.1
Ambicom WL250N-USB (Ralink RT3070 chipset)

Steps Overview

Assign a static IP to wlan0
Configure udhcpd as the DHCP server
Configure hostapd as the AP daemon
Enable IP forwarding and NAT between wlan0 and eth0
Wire it all up with systemd service files

1. Static IP for wlan0

ifconfig wlan0 192.168.0.1 up

2. udhcpd configuration

/etc/udhcpd.conf: