Thanks for the clarification, Heinrich. I appreciate your help.
I'll try putting ftdi_readstream in a pthread. It will field responses coming back from the network modules and keep a shared memory structure updated with the system state. -- Rick ________________________________ From: Heinrich du Toit <[email protected]> Sent: Thursday, May 31, 2018 10:37:24 PM To: [email protected] Subject: RE: Question about ftdi_readstream() Ftdi_readstream is a callback. If you go look at the code this will be obvious. If you want “background” or “async” I/O you should use ftdi_write_data_submit and ftdi_read_data_submit followed later by ftdi_transfer_data_done. Note that ftdi_transfer_data_done is also a blocking call. Alternatively you can use ftdi_readstream in a thread… this is called blocking I/O normally. Heinrich du Toit Specialist Engineer: Software [cid:emailfooterbase_93ec2d11-74f4-4d98-9ea6-a2dc6dcb552e.png]<http://www.s-plane.com> Disclaimers are available at: http://www.s-plane.com/disclaimer From: [email protected] <[email protected]> Sent: Friday, 01 June 2018 4:37 AM To: [email protected] Subject: Question about ftdi_readstream() Hi, I'm trying to get ftdi_readstream() working but must have some fundamental misunderstanding. I'd like it to work in the background (or in another thread) and simply parse data while I am free to use ftdi_write_data() to send commands to my application. I declare a handler that simply prints data to the console: static int readcallback(uint8_t *buffer, int length, FTDIProgressInfo *progress, void *userdata) { int i; printf("callback! %d\n", length); if (length) { for (i = 0; i < length; i ++) { printf("%d 0x%2x\n", i, buffer[i]); } } return (exitRequested ? 1 : 0); } Then I register the callback: err = ftdi_readstream(&ftdic, readcallback, NULL, 8, 256); printf("error: %d\n", err); if (err < 0 && !exitRequested) { exit(1); } ftdi_readstream() never returns. I was expecting it to create a separate thread, and asynchronously handle incoming data. I expected that I could set it up and then start using ftdi_write_data() to send control requests to my application. Digging a little deeper, I can determine that my readcallback() routine gets called continuously at high speed with length=0. Do I have to start readcallback() in it's own thread myself? I am also unclear on the purpose of the 8,256 arguments. I thought it should get a callback on every transfer. Do the 8,256 arguments bundle these up into larger chunks? Can I set them to be 1,1 for minimal latency? Everything works fine if I simply do ftdi_write_data() followed by ftdi_read_data() in a while(1) loop. I'd just like to increase efficiency by making reads happen in the background. kind regards, -- Rick Walker ________________________________ libftdi - see http://www.intra2net.com/en/developer/libftdi for details. To unsubscribe send a mail to [email protected]<mailto:[email protected]> ________________________________ libftdi - see http://www.intra2net.com/en/developer/libftdi for details. To unsubscribe send a mail to [email protected]<mailto:[email protected]> -- libftdi - see http://www.intra2net.com/en/developer/libftdi for details. To unsubscribe send a mail to [email protected]
