FlapJackApps/libdivecomputer
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Treat the first byte of a packet as an ACK/NAK byte.

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The first byte of a packet seems to be an ACK/NAK byte, rather than a 
real packet header. The implementation of the transfer function is 
changed to match this observation.
This commit is contained in:
Jef Driesen 2008-06-30 09:22:05 +00:00
parent 16f12123a3
commit 03b186e88b
1 changed files with 72 additions and 43 deletions
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115
src/oceanic_atom2.c
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@ -14,6 +14,14 @@
message ("%s:%d: %s\n", __FILE__, __LINE__, expr); \
}
#define EXITCODE(rc) \
( \
rc == -1 ? OCEANIC_ERROR_IO : OCEANIC_ERROR_TIMEOUT \
)
#define ACK 0x5A
#define NAK 0xA5
#define RB_LOGBOOK_EMPTY 0x0230
#define RB_LOGBOOK_BEGIN 0x0240
#define RB_LOGBOOK_END 0x0A40
@ -60,16 +68,17 @@ oceanic_atom2_send (atom2 *device, const unsigned char command[], unsigned int c
static int
oceanic_atom2_transfer (atom2 *device, const unsigned char command[], unsigned int csize, unsigned char answer[], unsigned int asize, int handshake)
oceanic_atom2_transfer (atom2 *device, const unsigned char command[], unsigned int csize, unsigned char answer[], unsigned int asize)
{
assert (asize >= 2);
// Send the command to the device. If the device responds with an
// ACK byte, the command was received successfully and the answer
// (if any) follows after the ACK byte. If the device responds with
// a NAK byte, we try to resend the command a number of times before
// returning an error.
// Occasionally, the dive computer does not respond to a command.
// In that case we retry the command a number of times before
// returning an error. Usually the dive computer will respond
// again during one of the retries.
for (unsigned int i = 0;; ++i) {
unsigned int nretries = 0;
unsigned char response = NAK;
while (response == NAK) {
// Send the command to the dive computer.
int rc = oceanic_atom2_send (device, command, csize);
if (rc != OCEANIC_SUCCESS) {
@ -77,34 +86,47 @@ oceanic_atom2_transfer (atom2 *device, const unsigned char command[], unsigned i
return rc;
}
// Receive the response (ACK/NAK) of the dive computer.
rc = serial_read (device->port, &response, 1);
if (rc != 1) {
WARNING ("Failed to receive the answer.");
return EXITCODE (rc);
}
#ifndef NDEBUG
if (response != ACK)
message ("Received unexpected response (%02x).\n", response);
#endif
// Abort if the maximum number of retries is reached.
if (nretries++ >= MAXRETRIES)
break;
}
// Verify the response of the dive computer.
if (response != ACK) {
WARNING ("Unexpected answer start byte(s).");
return OCEANIC_ERROR_PROTOCOL;
}
if (asize) {
// Receive the answer of the dive computer.
rc = serial_read (device->port, answer, asize);
int rc = serial_read (device->port, answer, asize);
if (rc != asize) {
WARNING ("Failed to receive the answer.");
if (rc == -1)
return OCEANIC_ERROR_IO;
if (i < MAXRETRIES)
continue; // Retry.
return OCEANIC_ERROR_TIMEOUT;
return EXITCODE (rc);
}
// Verify the header of the package.
unsigned char header = (handshake ? 0xA5 : 0x5A);
if (answer[0] != header) {
WARNING ("Unexpected answer start byte(s).");
return OCEANIC_ERROR_PROTOCOL;
}
// Verify the checksum of the package.
// Verify the checksum of the answer.
unsigned char crc = answer[asize - 1];
unsigned char ccrc = oceanic_atom2_checksum (answer + 1, asize - 2, 0x00);
unsigned char ccrc = oceanic_atom2_checksum (answer, asize - 1, 0x00);
if (crc != ccrc) {
WARNING ("Unexpected answer CRC.");
return OCEANIC_ERROR_PROTOCOL;
}
return OCEANIC_SUCCESS;
}
return OCEANIC_SUCCESS;
}
@ -186,16 +208,25 @@ oceanic_atom2_handshake (atom2 *device)
if (device == NULL)
return OCEANIC_ERROR;
// Send the handshake to connect to the device.
unsigned char answer[3] = {0};
// Send the command to the dive computer.
unsigned char command[3] = {0xA8, 0x99, 0x00};
int rc = oceanic_atom2_transfer (device, command, sizeof (command), answer, sizeof (answer), 1);
if (rc != OCEANIC_SUCCESS)
int rc = oceanic_atom2_send (device, command, sizeof (command));
if (rc != OCEANIC_SUCCESS) {
WARNING ("Failed to send the command.");
return rc;
}
// Verify the handshake.
if (answer[1] != 0xA5) {
WARNING ("Unexpected handshake byte(s).");
// Receive the answer of the dive computer.
unsigned char answer[3] = {0};
rc = serial_read (device->port, answer, sizeof (answer));
if (rc != sizeof (answer)) {
WARNING ("Failed to receive the answer.");
return EXITCODE (rc);
}
// Verify the answer.
if (answer[0] != NAK || answer[1] != NAK || answer[2] != NAK) {
WARNING ("Unexpected answer byte(s).");
return OCEANIC_ERROR_PROTOCOL;
}
@ -222,9 +253,7 @@ oceanic_atom2_quit (atom2 *device)
rc = serial_read (device->port, answer, sizeof (answer));
if (rc != sizeof (answer)) {
WARNING ("Failed to receive the answer.");
if (rc == -1)
return OCEANIC_ERROR_IO;
return OCEANIC_ERROR_TIMEOUT;
return EXITCODE (rc);
}
// Verify the answer.
@ -246,17 +275,17 @@ oceanic_atom2_read_version (atom2 *device, unsigned char data[], unsigned int si
if (size < OCEANIC_ATOM2_PACKET_SIZE)
return OCEANIC_ERROR_MEMORY;
unsigned char answer[OCEANIC_ATOM2_PACKET_SIZE + 2] = {0};
unsigned char answer[OCEANIC_ATOM2_PACKET_SIZE + 1] = {0};
unsigned char command[2] = {0x84, 0x00};
int rc = oceanic_atom2_transfer (device, command, sizeof (command), answer, sizeof (answer), 0);
int rc = oceanic_atom2_transfer (device, command, sizeof (command), answer, sizeof (answer));
if (rc != OCEANIC_SUCCESS)
return rc;
memcpy (data, answer + 1, OCEANIC_ATOM2_PACKET_SIZE);
memcpy (data, answer, OCEANIC_ATOM2_PACKET_SIZE);
#ifndef NDEBUG
answer[OCEANIC_ATOM2_PACKET_SIZE + 1] = 0;
message ("ATOM2ReadVersion()=\"%s\"\n", answer + 1);
answer[OCEANIC_ATOM2_PACKET_SIZE] = 0;
message ("ATOM2ReadVersion()=\"%s\"\n", answer);
#endif
return OCEANIC_SUCCESS;
@ -279,16 +308,16 @@ oceanic_atom2_read_memory (atom2 *device, unsigned int address, unsigned char da
while (nbytes < size) {
// Read the package.
unsigned int number = address / OCEANIC_ATOM2_PACKET_SIZE;
unsigned char answer[OCEANIC_ATOM2_PACKET_SIZE + 2] = {0};
unsigned char answer[OCEANIC_ATOM2_PACKET_SIZE + 1] = {0};
unsigned char command[4] = {0xB1,
(number >> 8) & 0xFF, // high
(number ) & 0xFF, // low
0};
int rc = oceanic_atom2_transfer (device, command, sizeof (command), answer, sizeof (answer), 0);
int rc = oceanic_atom2_transfer (device, command, sizeof (command), answer, sizeof (answer));
if (rc != OCEANIC_SUCCESS)
return rc;
memcpy (data, answer + 1, OCEANIC_ATOM2_PACKET_SIZE);
memcpy (data, answer, OCEANIC_ATOM2_PACKET_SIZE);
#ifndef NDEBUG
message ("ATOM2Read(0x%04x,%d)=\"", address, OCEANIC_ATOM2_PACKET_SIZE);