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• Notes on bcm2835 - SPI

  David Brown • 07/25/2016 at 17:05 • 0 comments

  Some working notes regarding using bcm2835 for SPI control, as the CE1 line is used as an I/O line the following lines need to be commented out to prevent it being taken out of service;

  File bcm2835.h;
  line 329 => //BCM2835_SPI_CS1 = 1, ///< Chip Select 1
  line 330 => //BCM2835_SPI_CS2 = 2, ///< Chip Select 2 (ie pins CS1 and CS2 are asserted)

  File bcm2835.c;
  line 330 => //bcm2835_gpio_fsel(RPI_GPIO_P1_26, BCM2835_GPIO_FSEL_ALT0); // CE1
  line 347 => //bcm2835_gpio_fsel(RPI_GPIO_P1_26, BCM2835_GPIO_FSEL_INPT); // CE1

  I'll add instructions when this has been tested fully. There may be a more elegant way of implementing this.

  I need to check and see if the option to setup with (BCM2835_SPI_CS_NONE) and then call CS manually in the code would be an alternative.

• Setting up Hat EEPROM

  David Brown • 07/21/2016 at 15:53 • 3 comments

  This process is taken from Howto: Raspi HAT EEPROM and device-tree but corrected for a couple of syntax errors (using Raspbian).

  As a preliminary step, you need to activate videocore I2C. This is done by adding a line at the beginning of your /boot/config.txt file
  

  sudo nano /boot/config.txt

  then add

  dtparam=i2c_vc=on

  reboot

  First of all, you need to get EEPROM utils (to make EEPROM content and flash it) and device-tree compiler (dtc).
  

  git clone https://github.com/raspberrypi/hats.git
  sudo apt-get install device-tree-compiler

  Read more »

• 0.1" header version

  David Brown • 06/24/2016 at 16:18 • 0 comments

  I've re-jigged the board to suit 0.1" header pins, this should make it more useful for a variety of projects. Files and schematic will be added to the files section.

• Version v3.0

  David Brown • 05/02/2016 at 13:43 • 0 comments

  I've uploaded version v3.0 of the board which has the headers moved to prevent clash with the micro USB connector on the Pi. I have also added a PolyZen over voltage protection diode to the 5V inlet to add a degree of over voltage protection.

  Before I killed the Pi, the wifi adaptor plugged directly into the v2.0 board was working happily through the pogo pin connection to the header pads on the Pi.

• v2.0 board

  David Brown • 05/02/2016 at 00:11 • 0 comments

  well I've recieved the v2 boards from OSH and everything looks good. I've noticed one irritating issue, which is the micro USB ports on the zero stick out slightly, and clash with one of my headers, but is fine if run as a 90deg header under the board.

  The other issue was when I accidentally contacted my 5V converter against the shielding on a ribbon cable and fried (connected to 12V) the zero and I assume the level converters - oops. So I want to add some voltage protection in the form of a voltage protection diode.

  So I will make some adjustments and upload the finalised version.

  Bare board

  Populated board

  Board & Raspberry Pi Zero

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