SPI/SSP Slave on LPC13xx

Discussion created by lpcware Employee on Jun 15, 2016
Content originally posted in LPCWare by jldesigns on Wed Nov 19 14:47:47 MST 2014

I need to communicate between LPC13xx through SPI in slave mode with another MCU (master mode).

The questions are:
1. Can I use (will there be any benefit using) SSEL pin on the MCU and connect it to master (as CS/SSEL pin of slave)? Or should I use normal GPIO interrupt within the LPC and start receiving on the SPI? Are there any traps using hardware SSEL like in master mode (it toggles every 1 frame etc.)?
2. First byte transmitted by MCU will be a kind of "command" byte. If command is 0x01 (set output state) then following bytes will cause GPIO change to receive value. If the command will be 0x71 (read current output state) then slave should send current state back. Whats the best way to approach this?

In my opinion the slave mode is weekley documented in user manual.

Thanks in advance.