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KSDK v1.3 UART_DRV_Edma driver questions (k22F, FreeRTOS)

Question asked by TERRY COOKE on Jan 28, 2016

I have an interesting case where I use the non-blocking function UART_DRV_EdmaReceiveData to receive 64 bytes. What I receive can either be 64 bytes or 4bytes.


To deal with the 4 byte packet, I continuously call UART_DRV_EdmaGetReceiveStatus from a task. When I have received at least 4 bytes (when bytesRemaiining < 61) I check the first byte received to determine if it is a small or big packet. I have verified with a debugger that bytesRemaining will tell me that I have received at least 4 bytes.


So if it is a small packet I call UART_DRV_EdmaAbortReceivingData, assuming that since byteRemaining reports that I have 4 bytes, I have received my whole small packet copied to my buffer.


What I have found however is that sometimes the Edma will not have actually copied the last couple of bytes into my buffer even though it says it has received 4 bytes. And when I call the UART_DRV_EdmaAbortReceivingData I never actually get the bytes it reports I received.


I understand this is not exactly how these drivers where intended, but can anyone explain what is happening? How can UART_DRV_EdmaGetReceiveStatus report I have 4 bytes, before they were actually copied?



Terry Cooke


2/19/2016: I am still waiting on a response to this, does anyone have any further infromation?