About the W5500 Ethernet chip, sending and receiving data bits

Question

Dear all: I looked at the W5500 example on github and found that buf in both the send() and recv() functions is handled in 8-bit terms. I was wondering if I could change this to a 16-bit unsigned char? Because I’m using DSP28335. The char for this platform is 16-bit.What do I need to change if I can? SPI changed to send receive 16 bits. There is also buf in send() and recv(). What else needs to be changed. Look forward to hearing from the official staff. 11155×920 41 KB 2952×918 36.3 KB 3732×639 202 KB

Eugeny · Answer

Network data is byte stream (not “char” stream in this terminology), and the library operates 8-bit byte values. I suspect you ask to save memory for this platform, if you declare char buf[1024] it will actually allocate 16x1024 bits of memory, while store only 8*1024 bits. In my opinion the best portable solution could be declaring your target array as uint8_t buf[1024]. But you need to test anyway to ensure routines copy data to/from your array properly.

Eugeny · Answer

What problem are you trying to solve or what are you trying to improve? SPI transmits one bit a time, not one byte or one character a time, and it does not matter if you feed the intermediate circuit with 8-bit data or 16-bit data - at the end they all are converted to bits.

Bohu-Tang · Answer

I think I’ve got an idea. I’ll give it a try. Thank you very much for your patient answer.