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#include "project.h"
#define DS18B20_CONVERT 0x44
#define DS18B20_WRITE_SCRATCHPAD 0x4e
#define DS18B20_READ_SCRATCHPAD 0xbe
#define TIMEOUT 150
unsigned extract_leu16 (uint8_t *d)
{
uint32_t u;
u = (uint32_t) d[0] | (((uint32_t) d[1]) << 8);
return u;
}
int extract_les16 (uint8_t *d)
{
uint32_t u;
u = extract_leu16 (d);
if (u & 0x8000) u |= 0xffff0000;
return (int) u;
}
/* do not call from interrupt context (ie ticker)*/
int
ds18b20_read_sp (const Onewire_addr *a, uint8_t *buf, unsigned len)
{
if (onewire_reset_and_select (a))
return ~0U;
onewire_write_byte (DS18B20_READ_SCRATCHPAD);
onewire_read_bytes (buf, len);
if ((len == 9) && onewire_check_crc (buf, 8, buf[8]))
return ~0U;
return 0;
}
int
ds18b20_write_sp (const Onewire_addr *a, uint8_t *buf, unsigned len)
{
if (onewire_reset_and_select (a))
return ~0U;
onewire_write_byte (DS18B20_WRITE_SCRATCHPAD);
onewire_write_bytes (buf, len);
return 0;
}
int ds18b20_convert (const Onewire_addr *a, unsigned timeout)
{
if (onewire_reset_and_select (a))
return ~0U;
onewire_write_byte (DS18B20_CONVERT);
if (timeout && onewire_wait_complete (timeout))
return ~0U;
return 0;
}
int
ds18b20_set_12 (const Onewire_addr *a)
{
uint8_t buf[9];
if (ds18b20_read_sp (a, buf, 9))
return 1;
buf[0] = 0x0;
buf[1] = 0x0;
buf[2] = 0x7f; /* 12 bit conversions */
return ds18b20_write_sp (a, buf, 3);
}
int ds18b20_read (const Onewire_addr *a, int *temp)
{
uint8_t buf[9];
if (ds18b20_read_sp (a, buf, 9))
return 1;
*temp = (extract_les16 (buf) * 500) >> 3;
return 0;
}
int
ds18b20_set_12_convert (const Onewire_addr *a)
{
if (ds18b20_set_12 (a))
return 1;
if (ds18b20_convert (a, 0))
return 1;
return 0;
}
/* do not call from interrupt context (ie ticker)*/
int
ds18b20_set_12_convert_and_read (const Onewire_addr *a, int *temp)
{
if (ds18b20_set_12 (a))
return 1;
if (ds18b20_convert (a, TIMEOUT))
return 1;
return ds18b20_read (a, temp);
}
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