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Diffstat (limited to 'dtt/ds1621.c')
| -rw-r--r-- | dtt/ds1621.c | 191 |
1 files changed, 191 insertions, 0 deletions
diff --git a/dtt/ds1621.c b/dtt/ds1621.c new file mode 100644 index 0000000..5c25f64 --- /dev/null +++ b/dtt/ds1621.c @@ -0,0 +1,191 @@ +/* + * (C) Copyright 2001 + * Erik Theisen, Wave 7 Optics, etheisen@mindspring.com. + * + * See file CREDITS for list of people who contributed to this + * project. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation; either version 2 of + * the License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, + * MA 02111-1307 USA + */ + +/* + * Dallas Semiconductor's DS1621 Digital Thermometer and Thermostat. + */ + +#include <common.h> + +#ifdef CONFIG_DTT_DS1621 +#if !defined(CFG_EEPROM_PAGE_WRITE_ENABLE) || \ + (CFG_EEPROM_PAGE_WRITE_BITS < 1) +# error "CFG_EEPROM_PAGE_WRITE_ENABLE must be defined and CFG_EEPROM_PAGE_WRITE_BITS must be greater than 1 to use CONFIG_DTT_DS1621" +#endif +#include <i2c.h> +#include <dtt.h> + +/* + * Device code + */ +#define DTT_I2C_DEV_CODE 0x48 /* Dallas Semi's DS1621 */ + +int dtt_read(int sensor, int reg) +{ + int dlen; + uchar data[2]; + + /* + * Calculate sensor address and command. + * + */ + sensor = DTT_I2C_DEV_CODE + (sensor & 0x07); /* Calculate addr of ds1621*/ + + /* + * Prepare to handle 2 byte result. + */ + if ((reg == DTT_READ_TEMP) || + (reg == DTT_TEMP_HIGH) || (reg == DTT_TEMP_LOW)) + dlen = 2; + else + dlen = 1; + + /* + * Now try to read the register. + */ + if (i2c_read(sensor, reg, 1, data, dlen) != 0) + return 1; + + /* + * Handle 2 byte result. + */ + if (dlen == 2) + return ((int)((short)data[1] + (((short)data[0]) << 8))); + + return (int)data[0]; +} /* dtt_read() */ + + +int dtt_write(int sensor, int reg, int val) +{ + int dlen; + uchar data[2]; + + /* + * Calculate sensor address and register. + * + */ + sensor = DTT_I2C_DEV_CODE + (sensor & sensor); + + /* + * Handle various data sizes. + */ + if ((reg == DTT_READ_TEMP) || + (reg == DTT_TEMP_HIGH) || (reg == DTT_TEMP_LOW)) { + dlen = 2; + data[0] = (char)((val >> 8) & 0xff); /* MSB first */ + data[1] = (char)(val & 0xff); + } + else if ((reg == DTT_WRITE_START_CONV) || (reg == DTT_WRITE_STOP_CONV)) { + dlen = 0; + data[0] = (char)0; + data[1] = (char)0; + } + else { + dlen = 1; + data[0] = (char)(val & 0xff); + } + + /* + * Write value to device. + */ + if (i2c_write(sensor, reg, 1, data, dlen) != 0) + return 1; + + return 0; +} /* dtt_write() */ + + +static int _dtt_init(int sensor) +{ + int val; + + /* + * Setup High Temp. + */ + val = ((CFG_DTT_MAX_TEMP * 2) << 7) & 0xff80; + if (dtt_write(sensor, DTT_TEMP_HIGH, val) != 0) + return 1; + udelay(50000); /* Max 50ms */ + + /* + * Setup Low Temp - hysteresis. + */ + val = (((CFG_DTT_MAX_TEMP - CFG_DTT_HYSTERESIS) * 2) << 7) & 0xff80; + if (dtt_write(sensor, DTT_TEMP_LOW, val) != 0) + return 1; + udelay(50000); /* Max 50ms */ + + /* + * Setup configuraton register + * + * Clear THF & TLF, Reserved = 1, Polarity = Active Low, One Shot = YES + * + * We run in polled mode, since there isn't any way to know if this + * lousy device is ready to provide temperature readings on power up. + */ + val = 0x9; + if (dtt_write(sensor, DTT_CONFIG, val) != 0) + return 1; + udelay(50000); /* Max 50ms */ + + return 0; +} /* _dtt_init() */ + + +int dtt_init (void) +{ + int i; + unsigned char sensors[] = CONFIG_DTT_SENSORS; + + for (i = 0; i < sizeof(sensors); i++) { + if (_dtt_init(sensors[i]) != 0) + printf("DTT%d: FAILED\n", i+1); + else + printf("DTT%d: %i C\n", i+1, dtt_get_temp(sensors[i])); + } + + return (0); +} /* dtt_init() */ + + +int dtt_get_temp(int sensor) +{ + int i; + + /* + * Start a conversion, may take up to 1 second. + */ + dtt_write(sensor, DTT_WRITE_START_CONV, 0); + for (i = 0; i <= 10; i++) { + udelay(100000); + if (dtt_read(sensor, DTT_CONFIG) & 0x80) + break; + } + + return (dtt_read(sensor, DTT_READ_TEMP) / 256); +} /* dtt_get_temp() */ + + +#endif /* CONFIG_DTT_DS1621 */ + |