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When the LM73 temperature sensor measures a temperature below 0 C, the current driver does not perform sign extension, so the result returned is 512 C too high. This patch fixes the problem, and does general cleanup of the code. Signed-off-by: Larry Johnson <lrj@acm.org>
172 lines
3.7 KiB
C
172 lines
3.7 KiB
C
/*
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* (C) Copyright 2007-2008
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* Larry Johnson, lrj@acm.org
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*
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* based on dtt/lm75.c which is ...
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*
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* (C) Copyright 2001
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* Bill Hunter, Wave 7 Optics, williamhunter@mediaone.net
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*
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* See file CREDITS for list of people who contributed to this
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* project.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of
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* the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
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* MA 02111-1307 USA
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*/
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/*
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* National Semiconductor LM73 Temperature Sensor
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*/
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#include <common.h>
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#include <i2c.h>
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#include <dtt.h>
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/*
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* Device code
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*/
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#define DTT_I2C_DEV_CODE 0x48 /* National Semi's LM73 device */
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int dtt_read(int const sensor, int const reg)
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{
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int dlen;
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uint8_t data[2];
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/*
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* Validate 'reg' param and get register size.
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*/
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switch (reg) {
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case DTT_CONFIG:
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case DTT_CONTROL:
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dlen = 1;
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break;
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case DTT_READ_TEMP:
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case DTT_TEMP_HIGH:
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case DTT_TEMP_LOW:
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case DTT_ID:
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dlen = 2;
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break;
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default:
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return -1;
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}
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/*
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* Try to read the register at the calculated sensor address.
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*/
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if (0 !=
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i2c_read(DTT_I2C_DEV_CODE + (sensor & 0x07), reg, 1, data, dlen))
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return -1;
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/*
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* Handle 2 byte result.
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*/
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if (2 == dlen)
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return (int)((unsigned)data[0] << 8 | (unsigned)data[1]);
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return (int)data[0];
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} /* dtt_read() */
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int dtt_write(int const sensor, int const reg, int const val)
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{
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int dlen;
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uint8_t data[2];
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/*
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* Validate 'reg' param and handle register size
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*/
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switch (reg) {
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case DTT_CONFIG:
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case DTT_CONTROL:
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dlen = 1;
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data[0] = (uint8_t) val;
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break;
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case DTT_TEMP_HIGH:
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case DTT_TEMP_LOW:
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dlen = 2;
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data[0] = (uint8_t) (val >> 8); /* MSB first */
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data[1] = (uint8_t) val;
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break;
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default:
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return -1;
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}
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/*
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* Write value to register at the calculated sensor address.
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*/
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return 0 != i2c_write(DTT_I2C_DEV_CODE + (sensor & 0x07), reg, 1, data,
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dlen);
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} /* dtt_write() */
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static int _dtt_init(int const sensor)
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{
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int val;
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/*
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* Validate the Identification register
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*/
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if (0x0190 != dtt_read(sensor, DTT_ID))
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return -1;
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/*
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* Setup THIGH (upper-limit) and TLOW (lower-limit) registers
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*/
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val = CFG_DTT_MAX_TEMP << 7;
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if (dtt_write(sensor, DTT_TEMP_HIGH, val))
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return -1;
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val = CFG_DTT_MIN_TEMP << 7;
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if (dtt_write(sensor, DTT_TEMP_LOW, val))
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return -1;
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/*
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* Setup configuraton register
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*/
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/* config = alert active low, disabled, and reset */
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val = 0x64;
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if (dtt_write(sensor, DTT_CONFIG, val))
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return -1;
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/*
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* Setup control/status register
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*/
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/* control = temp resolution 0.25C */
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val = 0x00;
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if (dtt_write(sensor, DTT_CONTROL, val))
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return -1;
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dtt_read(sensor, DTT_CONTROL); /* clear temperature flags */
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return 0;
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} /* _dtt_init() */
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int dtt_init(void)
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{
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int i;
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unsigned char sensors[] = CONFIG_DTT_SENSORS;
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const char *const header = "DTT: ";
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for (i = 0; i < sizeof(sensors); i++) {
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if (0 != _dtt_init(sensors[i]))
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printf("%s%d FAILED INIT\n", header, i + 1);
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else
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printf("%s%d is %i C\n", header, i + 1,
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dtt_get_temp(sensors[i]));
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}
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return 0;
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} /* dtt_init() */
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int dtt_get_temp(int const sensor)
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{
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int const ret = dtt_read(sensor, DTT_READ_TEMP);
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if (ret < 0) {
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printf("DTT temperature read failed.\n");
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return 0;
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}
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return (int)((int16_t) ret + 0x0040) >> 7;
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} /* dtt_get_temp() */
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