/* * (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 DS1621/1631 Digital Thermometer and Thermostat. */ #include <common.h> #include <i2c.h> #include <dtt.h> /* * Device code */ #define DTT_I2C_DEV_CODE 0x48 /* Dallas Semi's DS1621 */ #define DTT_READ_TEMP 0xAA #define DTT_READ_COUNTER 0xA8 #define DTT_READ_SLOPE 0xA9 #define DTT_WRITE_START_CONV 0xEE #define DTT_WRITE_STOP_CONV 0x22 #define DTT_TEMP_HIGH 0xA1 #define DTT_TEMP_LOW 0xA2 #define DTT_CONFIG 0xAC /* * Config register bits */ #define DTT_CONFIG_1SHOT 0x01 #define DTT_CONFIG_POLARITY 0x02 #define DTT_CONFIG_R0 0x04 /* ds1631 only */ #define DTT_CONFIG_R1 0x08 /* ds1631 only */ #define DTT_CONFIG_NVB 0x10 #define DTT_CONFIG_TLF 0x20 #define DTT_CONFIG_THF 0x40 #define DTT_CONFIG_DONE 0x80 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 */ switch(reg) { case DTT_READ_TEMP: case DTT_TEMP_HIGH: case DTT_TEMP_LOW: dlen = 2; break; default: 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 (short)((data[0] << 8) | data[1]); return (int)data[0]; } 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 & 0x07); /* Handle various data sizes. */ switch(reg) { case DTT_READ_TEMP: case DTT_TEMP_HIGH: case DTT_TEMP_LOW: dlen = 2; data[0] = (char)((val >> 8) & 0xff); /* MSB first */ data[1] = (char)(val & 0xff); break; case DTT_WRITE_START_CONV: case DTT_WRITE_STOP_CONV: dlen = 0; data[0] = (char)0; data[1] = (char)0; break; default: dlen = 1; data[0] = (char)(val & 0xff); } /* Write value to device */ if (i2c_write(sensor, reg, 1, data, dlen) != 0) return 1; /* Poll NV memory busy bit in case write was to register stored in EEPROM */ while(i2c_reg_read(sensor, DTT_CONFIG) & DTT_CONFIG_NVB) ; return 0; } int dtt_init_one(int sensor) { int val; /* Setup High Temp */ val = ((CONFIG_SYS_DTT_MAX_TEMP * 2) << 7) & 0xff80; if (dtt_write(sensor, DTT_TEMP_HIGH, val) != 0) return 1; /* Setup Low Temp - hysteresis */ val = (((CONFIG_SYS_DTT_MAX_TEMP - CONFIG_SYS_DTT_HYSTERESIS) * 2) << 7) & 0xff80; if (dtt_write(sensor, DTT_TEMP_LOW, val) != 0) return 1; /* * 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; return 0; } 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) & DTT_CONFIG_DONE) break; } return (dtt_read(sensor, DTT_READ_TEMP) / 256); }