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#include "project.h"
#define GPIO_PORT GPIOB
#define GPIO GPIO1
#define BIT_ZERO '0'
#define BIT_ONE '1'
#define BIT_UNKNOWN 'U'
#define BIT_CONFLICT 'C'
static inline void
low (void)
{
CLEAR (GPIO);
}
static inline void
hiz (void)
{
SET (GPIO);
}
static inline int
get (void)
{
return ! !GET (GPIO);
}
/*Returns 1 if timeout - waits ~100ms */
static inline int
wait_hiz (void)
{
unsigned int timeout = 10000;
hiz();
while (!get()) {
timeout--;
if (! (timeout--))
return 1;
delay_us (10);
}
return 0;
}
/* returns 1 if nothing on bus or error */
int
onewire_reset (void)
{
int ret;
cm_disable_interrupts();
low();
delay_us (600);
hiz();
delay_us (65);
ret = get();
if (wait_hiz())
ret = 1;
delay_us (100);
cm_enable_interrupts();
return ret;
}
void
onewire_one (void)
{
cm_disable_interrupts();
low();
delay_us (10);
hiz();
delay_us (90);
cm_enable_interrupts();
}
void
onewire_zero (void)
{
cm_disable_interrupts();
low();
delay_us (90);
hiz();
delay_us (10);
cm_enable_interrupts();
}
int
onewire_read (void)
{
int ret;
cm_disable_interrupts();
low();
delay_us (10);
hiz();
delay_us (20);
ret = get();
delay_us (70);
cm_enable_interrupts();
return ret;
}
void
onewire_write_byte (uint8_t v)
{
int c;
for (c = 0; c < 8; ++c) {
if (v & 1)
onewire_one();
else
onewire_zero();
v >>= 1;
}
}
uint8_t
onewire_read_byte (void)
{
uint8_t v = 0;
int c;
for (c = 0; c < 8; ++c) {
v >>= 1;
if (onewire_read())
v |= 0x80;
}
return v;
}
void
onewire_read_bytes (uint8_t *buf, int n)
{
while (n--)
* (buf++) = onewire_read_byte();
}
void
onewire_write_bytes (const uint8_t *buf, int n)
{
while (n--)
onewire_write_byte (* (buf++));
}
int onewire_select (const Onewire_addr *a)
{
if (!a)
onewire_write_byte (ONEWIRE_SKIP_ROM);
else {
onewire_write_byte (ONEWIRE_MATCH_ROM);
onewire_write_bytes (a->a, 8);
}
return 0;
}
int onewire_reset_and_select (const Onewire_addr *a)
{
if (onewire_reset())
return 1;
if (onewire_select (a))
return 1;
return 0;
}
int onewire_wait_complete (unsigned timeout)
{
while (! (onewire_read())) {
delay_ms (10);
if (! (timeout--))
return 1;
}
return 0;
}
int
onewire_check_crc (uint8_t *buf, int n, uint8_t v)
{
uint8_t crc = 0;
int i;
while (n--) {
uint8_t v = * (buf++);
for (i = 0; i < 8; ++i) {
uint8_t mix = (crc ^ v) & 0x01;
crc >>= 1;
if (mix)
crc ^= 0x8C;
v >>= 1;
}
}
return ! (crc == v);
}
static int onewire_conduct_search (uint8_t *bits)
{
unsigned i, ir, r;
if (onewire_reset())
return -1;
onewire_write_byte (ONEWIRE_SEARCH_ROM);
for (i = 0; i < 64; ++i) {
r = onewire_read();
ir = onewire_read();
#if 0
if ((i == 27) || (i == 24) || (i == 39))
ir = r = 0;
#endif
switch (bits[i]) {
case BIT_UNKNOWN:
if (!r && ir) { /* Zero */
bits[i] = BIT_ZERO;
onewire_zero();
} else if (r && !ir) { /*One */
bits[i] = BIT_ONE;
onewire_one();
} else if (r && ir) /*Nothing here */
return -1;
else if (!r && !ir) { /*Both */
bits[i] = BIT_CONFLICT;
onewire_zero();
}
break;
case BIT_CONFLICT:
if (!r && !ir) /*Both */
onewire_zero();
else
return -1;
break;
case BIT_ZERO:
if (!r)
onewire_zero();
else
return -1;
break;
case BIT_ONE:
if (!ir)
onewire_one();
else
return -1;
break;
}
}
return 0;
}
static int onewire_next (uint8_t *bits)
{
unsigned i;
for (i = 0; i < 64; ++i) {
if (bits[63 - i] == BIT_CONFLICT) {
bits[63 - i] = BIT_ONE;
return 1;
}
bits[63 - i] = BIT_UNKNOWN;
}
return 0;
}
static void onewire_bits_to_a (uint8_t *bits, Onewire_addr *a)
{
unsigned i, j, c;
for (i = 0, j = 0; i < 8; ++i) {
a->a[i] = 0;
for (c = 1; c < 0x100; c <<= 1, ++j) {
if (bits[j] == BIT_ONE)
a->a[i] |= c;
}
}
}
int onewire_search (void)
{
uint8_t bits[64];
Onewire_addr a;
int r, c;
printf ("One wire search\n");
//delay_ms (2000);
memset (bits, BIT_UNKNOWN, sizeof (bits));
do {
r = onewire_conduct_search (bits);
if (!r) {
onewire_bits_to_a (bits, &a);
c = onewire_check_crc (&a.a[0], 7, a.a[7]);
if (!c) {
printf ("O: {0x%02x,0x%02x,0x%02x,0x%02x,0x%02x,0x%02x,0x%02x,0x%02x}\r\n",
a.a[0],
a.a[1],
a.a[2],
a.a[3],
a.a[4],
a.a[5],
a.a[6],
a.a[7]);
}
}
} while (onewire_next (bits));
return 0;
}
void
onewire_init (void)
{
MAP_OUTPUT_OD_SLOW (GPIO);
hiz();
delay_us (20);
printf ("hiz -> %d\n", get());
low();
delay_us (20);
printf ("low -> %d\n", get());
hiz();
delay_us (20);
}
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