Posts Tagged BusPirate
As part of my GPS Logger project I needed to make sure that I could initialise and talk to a SD card over a SPI bus. The BusPirate is an excellent tool for testing the physical and datalink layers. All parameters can be checked and adjusted on the fly without having to write any code. When the time comes to write code for the GPS logger, it will work first time as all the kinks and quirks were quickly worked out with the BusPirate.
This post covers SPI bus setup, card initialisation, reading and writing individual sectors.
The system is now up and running. It is capable of communicating with the GPS receiver to get it into a known protocol (NMEA) and baud rate from an arbitrary starting configuration. I had to determine the pinout for the receiver as it was a USB GPS receiver. A check with the multimeter quickly identified the pinout of the four wires, TX was easy to spot as it was a constantly changing voltage whereas RX only changed when a command was sent. Once the prototyping is finished the USB receiver will be restored to its former glory. A few challenges were involved in figuring out the receivers startup configuration. It looks like at reset it outputs NMEA at 4800 baud but expects to receive NMEA configuration commands at 9600. This ‘interesting’ configuration was overcome by sending NMEA and SiRF configuration commands to the receiver at all supported baud rates. Read the rest of this entry »