Subg Rfspy SPI details
- cc1110 runs subg_rfspy firmware.
- Controlled via SPI (cc1110 is slave)
- SPI settings: LSB first, 8 bits per transfer, CPOL = 0 (negative), CPHA = 0 (phase = leading clock edge)
- Standard bitrate: 57200 bps
SPI master initiates a size transfer; the first byte of MOSI a token of 0x99, followed by the size of data that master wishes to send. The slave response on MISO is an ignored byte, followed by the size of data the slave has to send. If either of those size bytes are > 0, then a data transfer follows, otherwise at a later point master will initiate another size transfer to send data or see if the slave has any data to send.
The ensuing data transfer will be the max of the master's data size and the slave's data size:
The overview of the whole the transfer looks like this, which gives an idea of the timing. The data transfer is split up into two parts, but that is not necessary, and the whole 15 bytes could have been transferred continuosly.
