Connect the Cyton board to a FPGA
posting on behalf of a user:
"We are using a Cyton 8-channel Biosensing board for our senior design project.
We want to connect the Cyton board to a FPGA. The intent is to do the signal processing on a FPGA.
From what I understand we can only a SPI interface to communicate with any external hardware. As this is the only interface supported by the MCU on the Cyton board.
Can you please provide us with some information on how the bit order will look like? Since there is only one data out line, we want to understand how we can separate the data from 8 channels
Thank you."
Comments
Suggest that the customer look at the "serial1" information here,
https://github.com/OpenBCI/OpenBCI_Cyton_Library#referenceGuide
Functions beginDebug() and xxxSerial1(), where xxx is a wild card match.
The Cyton PIC32 (chipKIT) has TWO serial ports. One is used to communicate with the mainboard RFduino, to receive commands and send radio packets. The other serial port can be used for debug information BUT ALSO, you can have the Cyton data output stream directed to this other Serial1 port, instead of the default Serial0. The Cyton serial port commands and data stream are described on the docs site,
https://docs.openbci.com/docs/02Cyton/CytonDataFormat
https://docs.openbci.com/docs/02Cyton/CytonSDK
With a slightly modified firmware, your Cyton can receive commands on the Serial1 port and send data stream to Serial1. Your FPGA could easily be connected to this serial port.
Regards, William
Since the Cyton is SPI master, using SPI with your FPGA will be problematic. Since the FPGA is essentially a master process / controller, running the signal processing and getting data from Cyton. This is why the serial port will give you the same interface all other apps use to interface with Cyton.