Stathis Voukelatos

Using the i.MX28 SSP without DMA

Discussion created by Stathis Voukelatos on Jun 13, 2012
Latest reply on Jun 14, 2012 by Stathis Voukelatos
Hi all, It is not clear to me what is the right way to transfer data to/from the SSP without using DMA. The general method for reading data is to poll the FIFO_EMPTY bit of the SSP_STATUS register and then read the actual data from the SSP_DATA register. However, when the status bit gets cleared can we always assume that we can read 4 bytes of data from the SSP_DATA register or anything between 1 and 4 bytes maybe available? The same issue exists when we want to write data to the SSP in which case we poll the FIFO_FULL status bit before doing a write to the data register. The available SPI drivers for the i.MX28 seem to program the SSP to do single byte transfers and therefore do no run into this issue. However this is not efficient.