I’m communicating with the ALFAT USB board from the RS232 port of an industrial device (MAX232 level converter in between). I have SPI_SCK, SPI_MOSI, and SPI_SSEL pulled low to force 9600 baud and UART mode. The host device has no other I/O available so I’m not able to monitor the UART_BUSY pin. Everything is working fine so I’m wondering how important it is to watch the state of this pin? I’m transmitting small amounts of data at a time (say 500 bytes) and always at 9600 baud. I assume I’m not filling the ALFAT’s buffer which is why I haven’t encountered any problems, but is there any way to determine how far I could push it? At 9600 baud, could I send data continuously without overloading the buffer? I would guess the answer to be yes since the data is written to USB much faster than that, but are there other factors to consider?
@ kolyur -
Busy pin is not necessary if you don’t have any extra IO in host.
You can poll from the host to see when a command is finished.
- Example for Format command, assuming 1GB takes 1 minute, 8G take 2 mins. Busy pin will tell you when format is done. Without Busy pin, you can check your receive buffer every 1sec or 1ms etc…
- Same for write-read command, assuming write 10K data, old media takes 20ms, good media takes 10ms. Polling your receive buffer to see when writing is done if without using busy pin.
Accept for assessing a media, almost commands take same time to response, like get version, date and time…