Hello Thomas,
I did a ftdi_read_data_set_chunksize(ftdi, 513) and commented out
the purge, still the data I'm receiving is not 'correct' there are
512 positions (the 1st of the 513 array is the start code which is
always 0x00) which correspond to a DMX channel, and I keep getting
the correct value but always on the wrong array positions, they keep
changing.
Also, the break interrupt seems to be slower than what it should be.
Attached goes my latest test code.
Best regards,
On 05/30/2012 05:57 PM, Thomas Jarosch wrote:
Hi Rui,
On Wednesday, 30. May 2012 17:09:04 Rui Barreiros wrote:
while(!exitRequested) {
ftdi_poll_modem_status(ftdi, &status);
if(status & 0x1000) { // BREAK_INTERRUPT
f = ftdi_read_data(ftdi, buff, sizeof(buff));
if(f < 0)
sleep(1);
else if(f > 0) {
ftdi_usb_purge_rx_buffer(ftdi);
fprintf(stdout, "Read %d bytes\n", f);
for(i = 0; i < sizeof(buff); i++) {
fprintf(stdout, "%02X ", ((unsigned char *) buff)[i] );
}
I'm not sure if the ftdi_usb_purge_rx_buffer() is a good idea:
ftdi_read_data() reads data in "readbuffer_chunksize" blocks,
usually 4096 bytes. If the "sizeof(buff)" (=513) is smaller than that
and the chip returns more data, it will be buffered internally.
Next time you call ftdi_read_data(), it might return data
from the internal read buffer. The problem is that
ftdi_usb_purge_rx_buffer() clears the internal read buffer,
so you will experience data loss.
Do you really need ftdi_usb_purge_rx_buffer()?
Thomas
--
Rui Barreiros
rui.barreiros@xxxxxxxxxxxx
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test.c
Description: Text Data
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