Which is the max clock rate for SPI in slave mode (at the hardware level) ?
Tegra2 NVIDIA datasheet reports for general SPI : Maximum transfer rate is 50 Mbits/sec.
Is this correct even for SPI in slave mode ?
Thank you for your attention.
Michele.
Yes, the Tegra 2 TRM (Technical Reference Manual) mentions the same 50 Mbits/sec without indicated anything about whether master or slave mode is used. However be aware that SPI slave operation has some limitations which e.g. the attempt at a mainline driver describes as follows:
Due to the nature of SPI slave (simultaneous transmit and receive, while everything runs at the pace of the master), it has hard real-time requirements: once an SPI transfer is started by the SPI master, a software SPI slave must have prepared all data to be sent back to the SPI master. Hence without additional hardware support, an SPI slave response can never be a reply to a command being simultaneously transmitted, and SPI slave replies must be received by the SPI master in a subsequent SPI transfer.
