I am using MCP2210 in my project to communicate with a processor (TMS320F28377D from TI).
For tests, I use SPI Terminal programm from microchip. However there are some issues.
There are some settings for delays, CS-to-Data, Data-to-Data, LastData-to-CS delay. I set everything to zero, although there are always delays if I use high speed SPI for example 1MBit/s.
I attach screenshoots and osci picture.
This is SPI Terminal screenshoot. I send zeros just for testing. I use 32 Byte transfer and as you can see, all delays are set to zero.
This is MCP2210 Utility programm. I read back the configurations, they are set correctly.
If I send data, there are huge delays between Cs-to-Data, Data-to-Data and LastData-to-CS (not shown in picture).
Green is SPI clock
Yellow is Chip Select
Light blue is MOSI (MCP2210 is Master)
Purple is MISO (TMS processor is Slave)
Why is it so?
Thanks.
Best Answer
The delays happen because the MCP22xx family of devices is allegedly based on general-purpose PIC16F145x MCU. This MCU has only a 8-bit hardware to convert a byte into serial code, Master Synchronous Serial Port (MSSP) module. The converter is only 8 bit, and there is no DMA or else. So every transfer must be firmware-initiated, byte by byte, that's why the delays. Plus USB overhead. As result, there are gaps about 30 us between bytes on the bus. This device looks like a kludge. There are numerous complaints about sluggish performance of these ICs on Internet.