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Change the echo cancellation to match with Suunto Dive Manager 1.6.

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Detection of the interface before reading or writing is not required 
anymore.
This commit is contained in:
Jef Driesen 2007-11-08 14:46:10 +00:00
parent 94ff25e8a4
commit 07265e3571
1 changed files with 18 additions and 18 deletions
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36
suunto_vyper.c
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@ -198,30 +198,30 @@ suunto_vyper_detect_interface (vyper *device)
static int
suunto_vyper_send_command (vyper *device, const unsigned char* data, unsigned int size)
{
// Send the command to the dive computer.
serial_sleep (500);
// Set RTS to send the command.
serial_set_rts (device->port, 1);
// Send the command to the dive computer and
// wait until all data has been transmitted.
serial_write (device->port, data, size);
serial_drain (device->port);
serial_sleep (200);
serial_set_rts (device->port, 0);
// If the interface sends an echo back (which is the case for many clone
// interfaces), those echos should be removed from the input queue before
// reading the real reply from the dive computer. Otherwise, the data
// transfer will fail.
if (device->ifacealwaysechos) {
// Echos should be there instantly.
unsigned char echo[37] = {0}; // An echo is maximum 37 bytes long.
int rc = serial_read (device->port, echo, size);
if (rc != size || memcmp (data, echo, size) != 0) {
if (rc == 0)
fprintf (stderr, "%s:%d: Timeout waiting for echos.\n", __FILE__, __LINE__);
else
fprintf (stderr, "%s:%d: Echo incorrect.\nMaybe another device is listening on this port?\n", __FILE__, __LINE__);
return -1;
}
}
// interfaces), this echo should be removed from the input queue before
// attempting to read the real reply from the dive computer. Otherwise,
// the data transfer will fail. Timing is also critical here! We have to
// wait at least until the echo appears (100ms), but not until the reply
// from the dive computer appears (600ms).
// The original suunto interface does not have this problem, because it
// does not send an echo and the RTS switching makes it impossible to
// receive the reply too early here.
serial_sleep (200);
serial_flush (device->port, SERIAL_QUEUE_INPUT);
// Clear RTS to receive the reply.
serial_set_rts (device->port, 0);
return 0;
}