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-rw-r--r--n/avr/twi-master/twi_master.c173
1 files changed, 173 insertions, 0 deletions
diff --git a/n/avr/twi-master/twi_master.c b/n/avr/twi-master/twi_master.c
new file mode 100644
index 0000000..ee556ca
--- /dev/null
+++ b/n/avr/twi-master/twi_master.c
@@ -0,0 +1,173 @@
+/* twi_master.c */
+#include "twi_master.h"
+
+#include <n/avr/rs232/rs232.h>
+#include <avr/twi.h>
+#include <avr/io.h>
+#include <avr/signal.h>
+#include <string.h>
+
+
+#define NB_ITER_WAIT 40000
+#define NB_RETRY 5
+
+static uint8_t buffer[TWI_BUF_SIZE];
+static uint8_t twi_dest_addr;
+static uint8_t twi_len;
+static uint8_t twi_idx;
+static uint8_t twi_nb_retry;
+uint8_t twi_state = 0;
+
+#define SYSCLK 14745600UL
+
+/* compteur 10 ms pour attente du bus 40 000 iterations */
+/* compteur x essais y ms secondes d'attende */
+void
+twi_master_init (void)
+{
+ /* initialize TWI clock: 100 kHz clock, TWPS = 0 => prescaler = 1 */
+#if defined(TWPS0)
+ TWSR = 0;
+#endif
+ TWBR = (SYSCLK / 100000UL - 16) / 2;
+ TWCR = _BV (TWEN) | _BV (TWIE);
+}
+
+int8_t
+twi_master_send (uint8_t addr, uint8_t data[], uint8_t len)
+{
+ rs232_putc ('a');
+ twi_state = 0;
+ twi_nb_retry = 0;
+ if (len > TWI_BUF_SIZE)
+ return -1;
+ twi_dest_addr = addr & 0xfe;
+ twi_len = len;
+ memcpy (buffer, data, len);
+ /* envoie du start */
+ TWCR |= _BV(TWSTA);
+ TWCR |= _BV(TWINT);
+ rs232_putc ('b');
+ while (!twi_state)
+ ;
+ rs232_putc ('c');
+ return twi_state;
+}
+
+int8_t
+twi_master_read (uint8_t addr, uint8_t data[], uint8_t len)
+{
+ rs232_putc ('a');
+ twi_state = 0;
+ twi_nb_retry = 0;
+ if (len > TWI_BUF_SIZE)
+ return -1;
+ twi_dest_addr = addr | 0x01;
+ twi_len = len;
+ //TWCR &= ~_BV (TWSTO);
+ TWCR |= _BV(TWSTA) | _BV (TWINT);
+ rs232_putc ('z');
+ while (!twi_state)
+ ;
+ rs232_putc ('x');
+ memcpy (data, buffer, len);
+ rs232_putc ('w');
+ return twi_state;
+}
+
+SIGNAL (SIG_2WIRE_SERIAL)
+{
+ rs232_putc ('y');
+ switch (TW_STATUS)
+ {
+ /* Master */
+ case TW_START:
+ case TW_REP_START:
+ /* start transmis, on envoie l'adresse */
+ rs232_putc ('d');
+ TWCR &= ~ (_BV (TWSTA) | _BV (TWSTO) | _BV (TWINT));
+ TWDR = twi_dest_addr;
+ twi_idx = 0;
+ break;
+ case TW_MT_ARB_LOST: /* valable pour le receiver aussi */
+ /* todo */
+ rs232_putc ('e');
+ break;
+ /* Master Transmitter */
+ case TW_MT_DATA_ACK:
+ case TW_MT_SLA_ACK:
+ /* slave ok
+ * On envoi des données si il en reste
+ */
+ if (twi_idx < twi_len)
+ {
+ rs232_putc ('f');
+ TWDR = buffer[twi_idx ++];
+ }
+ else
+ {
+ TWCR |= _BV (TWSTO);
+ rs232_putc ('g');
+ twi_state = 1;
+ }
+ break;
+ case TW_MT_SLA_NACK:
+ /* le slave ne repond plus
+ * on essaye NB_RETRY avant d'arreter
+ */
+ if (twi_nb_retry < NB_RETRY)
+ {
+ rs232_putc ('h');
+ TWCR |= _BV (TWSTA);
+ twi_nb_retry ++;
+ }
+ else
+ {
+ rs232_putc ('i');
+ TWCR |= _BV (TWSTO);
+ twi_state = 2;
+ }
+ break;
+ case TW_MT_DATA_NACK:
+ /* le slave ne veut plus de donnée */
+ rs232_putc ('j');
+ TWCR |= _BV (TWSTO);
+ twi_state = 1;
+ break;
+ /* Master Receiver */
+ case TW_MR_SLA_ACK:
+ rs232_putc ('p');
+ if (twi_len > 1) /* on recoit plusieurs octet */
+ {
+ rs232_putc ('k');
+ TWCR |= _BV (TWEA);
+ }
+ break;
+ case TW_MR_SLA_NACK:
+ if (twi_nb_retry < NB_RETRY)
+ {
+ rs232_putc ('l');
+ TWCR |= _BV (TWEA);
+ }
+ else
+ {
+ rs232_putc ('m');
+ TWCR |= _BV (TWSTO);
+ twi_state = -2;
+ }
+ break;
+ case TW_MR_DATA_ACK:
+ buffer[twi_idx ++] = TWDR;
+ rs232_putc ('n');
+ if (twi_idx == (twi_len - 1))
+ TWCR |= _BV (TWEA);
+ break;
+ case TW_MR_DATA_NACK: /* dernier byte */
+ twi_state = 1;
+ rs232_putc ('o');
+ buffer[twi_idx ++] = TWDR;
+ TWCR |= _BV (TWSTO);
+ break;
+ }
+ TWCR |= _BV (TWINT);
+}