gurushen wrote on Thursday, June 13, 2013:
Hi, I need a queue structure for passing bytes for a uart driver. I was using the freertos queue implementation but a co-worker insist on writing our own queue struct. Is there any benefit of rewriting our own?
richard_damon wrote on Thursday, June 13, 2013:
It might be possible to write a slightly more efficient queue knowing that one end is alway an interrupt routine, and maybe some others knowable special cases (like it is always 1 byte at a time being sent, if that is how you are doing it). I am not sure if the improvements are worth the extra work and risk of bugs.
jakbird1 wrote on Saturday, June 15, 2013:
While the FreeRTOS queue works well and is easy to use it does have some drawbacks. It’s oriented toward one character at a time rather than block transfers. I did go the separate FIFO driver route in order to minimize interrupt overhead. I read and write blocks of data through a FIFO, also making use of DMA to reduce USART TX interrupts by as much as 100 to 1 (sending large Modbus messages).
If your data rate is low use the FreeRTOS queue, but if you have a high data rate your co-worker is right…roll your own buffer management. USART interrupt overhead can be significant.
Jack Peacock
rtel wrote on Saturday, June 15, 2013:
It’s oriented toward one character at a time rather than block transfers
A queue can be created to hold blocks of any size, although each block in a queue has to be the same size. To queue really large blocks you would queue a pointer to the block instead of the block itself.
The FreeRTOS queues are designed for their purpose.
Regards.