Nigel Spon

MCF5208 eDMA to UART bus error

Discussion created by Nigel Spon on May 18, 2007
Latest reply on May 20, 2007 by Nigel Spon
I'm using CW 6.3, writing code for an MCF5208.

I'm trying to drive UART 0 with the eDMA controller. I have set up a TCD for channel 2 (which is the transmit channel for UART 0) but a few microseconds after enabling the DMA requests, I get the DBE error bit set in EDMA_ES, saying that there was a bus error on the destination write for channel 2. This is rather mysterious as I can then read back from the TCD and confirm that DADDR is set to 0xFC06000C (the UART 0 TBD) and that ATTR is set to 0, specifying an 8-bit wide source and destination transfer size. Is there something else I need to do to persuade the eDMA controller to write to the UART? My own code can write to the UART 0 TBD without difficulty in the same context...