// Copies the serial_slave_buffer to the master and sends the
// serial_master_buffer to the slave.
//
// Returns:
// 0 => no error
// 1 => slave did not respond
int serial_update_buffers(void) {
// this code is very time dependent, so we need to disable interrupts
cli();
// signal to the slave that we want to start a transaction
serial_output();
serial_low();
_delay_us(1);
// wait for the slaves response
serial_input();
serial_high();
_delay_us(SERIAL_DELAY);
// check if the slave is present
if (serial_read_pin()) {
// slave failed to pull the line low, assume not present
sei();
return 1;
}
// if the slave is present syncronize with it
sync_recv();
uint8_t checksum_computed = 0;
// receive data from the slave
for (int i = 0; i < SERIAL_SLAVE_BUFFER_LENGTH; ++i) {
serial_slave_buffer[i] = serial_read_byte();
sync_recv();
checksum_computed += serial_slave_buffer[i];
}
uint8_t checksum_received = serial_read_byte();
sync_recv();
if (checksum_computed != checksum_received) {
sei();
return 1;
}
uint8_t checksum = 0;
// send data to the slave
for (int i = 0; i < SERIAL_MASTER_BUFFER_LENGTH; ++i) {
serial_write_byte(serial_master_buffer[i]);
sync_recv();
checksum += serial_master_buffer[i];
}
serial_write_byte(checksum);
sync_recv();
// always, release the line when not in use
serial_output();
serial_high();
sei();
return 0;
}
int get_num_files(serial_handle_t serial_handle) {
int r;
char reply[2];
// flush the serial port
r = serial_flush(serial_handle);
if (r < 0) {
return -1;
}
// send the command to request the number of recorded files
r = serial_write_byte(serial_handle, 0x01);
if (r < 1) {
return -1;
}
// read the reply, 2 bytes
r = serial_read(serial_handle, reply, 2, 500*1000);
if (r < 2) {
return -1;
}
g_debug("cmd 0x01 (get num files), 2-byte response: 0x%02x 0x%02x", reply[0], reply[1]);
// but only the second byte matters
return reply[1];
}
void ta(int pi)
{
int h, b, e;
char *TEXT;
char text[2048];
printf("Serial link tests.\n");
/* this test needs RXD and TXD to be connected */
h = serial_open(pi, "/dev/ttyAMA0", 57600, 0);
CHECK(10, 1, h, 0, 0, "serial open");
time_sleep(0.1); /* allow time for transmission */
b = serial_read(pi, h, text, sizeof(text)); /* flush buffer */
b = serial_data_available(pi, h);
CHECK(10, 2, b, 0, 0, "serial data available");
TEXT = "\
To be, or not to be, that is the question-\
Whether 'tis Nobler in the mind to suffer\
The Slings and Arrows of outrageous Fortune,\
Or to take Arms against a Sea of troubles,\
";
e = serial_write(pi, h, TEXT, strlen(TEXT));
CHECK(10, 3, e, 0, 0, "serial write");
e = serial_write_byte(pi, h, 0xAA);
e = serial_write_byte(pi, h, 0x55);
e = serial_write_byte(pi, h, 0x00);
e = serial_write_byte(pi, h, 0xFF);
CHECK(10, 4, e, 0, 0, "serial write byte");
time_sleep(0.1); /* allow time for transmission */
b = serial_data_available(pi, h);
CHECK(10, 5, b, strlen(TEXT)+4, 0, "serial data available");
b = serial_read(pi, h, text, strlen(TEXT));
CHECK(10, 6, b, strlen(TEXT), 0, "serial read");
if (b >= 0) text[b] = 0;
CHECK(10, 7, strcmp(TEXT, text), 0, 0, "serial read");
b = serial_read_byte(pi, h);
CHECK(10, 8, b, 0xAA, 0, "serial read byte");
b = serial_read_byte(pi, h);
CHECK(10, 9, b, 0x55, 0, "serial read byte");
b = serial_read_byte(pi, h);
CHECK(10, 10, b, 0x00, 0, "serial read byte");
b = serial_read_byte(pi, h);
CHECK(10, 11, b, 0xFF, 0, "serial read byte");
b = serial_data_available(pi, h);
CHECK(10, 12, b, 0, 0, "serial data availabe");
e = serial_close(pi, h);
CHECK(10, 13, e, 0, 0, "serial close");
}
