ADC overo 2.6.38-
For overo's running kernel 2.6.38 and earlier
Use /dev/twl4030 to access the adc's
See Scott Ellis' page
http://www.jumpnowtek.com/index.php?option=com_content&view=article&id=79&Itemid=91
The source code uses the ‘twl4030’ as a name - which is also an older chip from TI. The TPS65950 on the OMAP board is pin-compatible and uses the same/similar ADC module so the older code works nicely (no need to reinvent the wheel).
You can support the ‘twl4030’ in Linux is via a kernel module, which is the way you can access it directly via /dev/twl4030. The TPS65950 talks to the OMAP chip via I2C bus.
Save both files in the same directory then build
twl4030-madc.h
/* * include/linux/i2c/twl4030-madc.h * * TWL4030 MADC module driver header * * Copyright (C) 2008 Nokia Corporation * Mikko Ylinen <mikko.k.ylinen@...> * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * version 2 as published by the Free Software Foundation. * * 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., 51 Franklin St, Fifth Floor, Boston, MA * 02110-1301 USA * */ #ifndef _TWL4030_MADC_H #define _TWL4030_MADC_H struct twl4030_madc_conversion_method { u8 sel; u8 avg; u8 rbase; u8 ctrl; }; #define TWL4030_MADC_MAX_CHANNELS 16 struct twl4030_madc_request { u16 channels; u16 do_avg; u16 method; u16 type; int active; int result_pending; int rbuf[TWL4030_MADC_MAX_CHANNELS]; void (*func_cb)(int len, int channels, int *buf); }; enum conversion_methods { TWL4030_MADC_RT, TWL4030_MADC_SW1, TWL4030_MADC_SW2, TWL4030_MADC_NUM_METHODS }; enum sample_type { TWL4030_MADC_WAIT, TWL4030_MADC_IRQ_ONESHOT, TWL4030_MADC_IRQ_REARM }; #define TWL4030_MADC_CTRL1 0x00 #define TWL4030_MADC_CTRL2 0x01 #define TWL4030_MADC_RTSELECT_LSB 0x02 #define TWL4030_MADC_SW1SELECT_LSB 0x06 #define TWL4030_MADC_SW2SELECT_LSB 0x0A #define TWL4030_MADC_RTAVERAGE_LSB 0x04 #define TWL4030_MADC_SW1AVERAGE_LSB 0x08 #define TWL4030_MADC_SW2AVERAGE_LSB 0x0C #define TWL4030_MADC_CTRL_SW1 0x12 #define TWL4030_MADC_CTRL_SW2 0x13 #define TWL4030_MADC_RTCH0_LSB 0x17 #define TWL4030_MADC_GPCH0_LSB 0x37 #define TWL4030_MADC_MADCON (1<<0) /* MADC power on */ #define TWL4030_MADC_BUSY (1<<0) /* MADC busy */ #define TWL4030_MADC_EOC_SW (1<<1) /* MADC conversion completion */ #define TWL4030_MADC_SW_START (1<<5) /* MADC SWx start conversion */ #define TWL4030_MADC_ADCIN0 (1<<0) #define TWL4030_MADC_ADCIN1 (1<<1) #define TWL4030_MADC_ADCIN2 (1<<2) #define TWL4030_MADC_ADCIN3 (1<<3) #define TWL4030_MADC_ADCIN4 (1<<4) #define TWL4030_MADC_ADCIN5 (1<<5) #define TWL4030_MADC_ADCIN6 (1<<6) #define TWL4030_MADC_ADCIN7 (1<<7) #define TWL4030_MADC_ADCIN8 (1<<8) #define TWL4030_MADC_ADCIN9 (1<<9) #define TWL4030_MADC_ADCIN10 (1<<10) #define TWL4030_MADC_ADCIN11 (1<<11) #define TWL4030_MADC_ADCIN12 (1<<12) #define TWL4030_MADC_ADCIN13 (1<<13) #define TWL4030_MADC_ADCIN14 (1<<14) #define TWL4030_MADC_ADCIN15 (1<<15) /* Fixed channels */ #define TWL4030_MADC_BTEMP TWL4030_MADC_ADCIN1 #define TWL4030_MADC_VBUS TWL4030_MADC_ADCIN8 #define TWL4030_MADC_VBKB TWL4030_MADC_ADCIN9 #define TWL4030_MADC_ICHG TWL4030_MADC_ADCIN10 #define TWL4030_MADC_VCHG TWL4030_MADC_ADCIN11 #define TWL4030_MADC_VBAT TWL4030_MADC_ADCIN12 /* BCI related - XXX To be moved elsewhere */ #define TWL4030_BCI_BCICTL1 0x23 #define TWL4030_BCI_MESBAT (1<<1) #define TWL4030_BCI_TYPEN (1<<4) #define TWL4030_BCI_ITHEN (1<<3) #define TWL4030_MADC_IOC_MAGIC '`' #define TWL4030_MADC_IOCX_ADC_RAW_READ _IO(TWL4030_MADC_IOC_MAGIC, 0) struct twl4030_madc_user_parms { int channel; int average; int status; u16 result; }; int twl4030_madc_conversion(struct twl4030_madc_request *conv); #endif
Main program
/* Test code for the MADC function * * Hugo Vincent, May 2009 */ #include <sys/ioctl.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <stdio.h> #include <stdint.h> #include <string.h> #include <stdlib.h> #include <unistd.h> #include <errno.h> #include <time.h> typedef uint8_t u8; typedef uint16_t u16; #include "twl4030-madc.h" /* Note: (very weird) the madc driver seems to crash if you've got driver debugging * turned on in your defconfig... */ /* Channel numbering: * ADC0-1 : to do with battery charging, not relevant on Overo * ADC2-7 : general purpose, input range = 0 - 2.5V. * On Overo, ADC2 seems to read as ~0.4 and ADC7 as ~1.4V (?). * ADC8 : USB OTG port bus voltage. * ADC9-11 : more battery charging stuff, not relevant. * ADC12 : main battery voltage. * This will be the system 3.3V rail in our case * ADC13-15: reserved or not relevant. */ struct adc_channel { int number; char name[16]; float input_range; }; struct adc_channel channels[] = { { .number = 2, .name = "ADCIN2", .input_range = 2.5, }, { .number = 3, .name = "ADCIN3", .input_range = 2.5, }, { .number = 4, .name = "ADCIN4", .input_range = 2.5, }, { .number = 5, .name = "ADCIN5", .input_range = 2.5, }, { .number = 6, .name = "ADCIN6", .input_range = 2.5, }, { .number = 7, .name = "ADCIN7", .input_range = 2.5, }, { .number = 8, .name = "VBUS_USB_OTG", .input_range = 7.0, }, { .number = 12, .name = "VBATT/3.3V_RAIL", .input_range = 6.0, }, }; int main(int argc, char **argv) { int d = open("/dev/twl4030-madc", O_RDWR | O_NONBLOCK); if (d == -1) { printf("could not open device /dev/twl4030-madc \n"); EXIT_FAILURE; } struct twl4030_madc_user_parms *par; par = malloc(sizeof(struct twl4030_madc_user_parms)); for (j = 0; j < (sizeof(channels)/sizeof(struct adc_channel)); j++) { memset(par, 0, sizeof(struct twl4030_madc_user_parms)); par->channel = channels[j].number; int ret = ioctl(d, TWL4030_MADC_IOCX_ADC_RAW_READ, par); float result = ((unsigned int)par->result) / 1024.f; // 10 bit ADC -> 1024 if (ret == 0 && par->status != -1) { printf("%s (channel %d): %f\n", channels[j].name, channels[j].number,result * channels[j].input_range); } else { if (par->status == -1) printf("Channel %d (%s) timed out!\n", j, channels[j].name); printf("ERROR\n"); exit(1); } } return 0; }
compile it
gcc –o madc madc.c
root@overo:~# ./madc
ADCIN2 (channel 2): 0.673828
ADCIN3 (channel 3): 0.087891
ADCIN4 (channel 4): 0.612793
ADCIN5 (channel 5): 0.090332
ADCIN6 (channel 6): 0.341797
ADCIN7 (channel 7): 1.374512
VBUS_USB_OTG (channel 8): 5.154297
VBATT/3.3V_RAIL (channel 12): 3.275391
root@overo:~#
when using the ADCs you may/will need to scale values.
Vincent, H. (2009) ADC Code Example – Help with Overo ADC. http://old.nabble.com/Re%3A-Help-with-Overo-ADC-td24174607.html
TI TPS65950 Integrated Power Management/Audio Codec Data Manual http://focus.ti.com/lit/ds/symlink/tps65950.pdf
TI TPS65950 OMAP Power Management and System Companion Device Version G Technical Reference Manual http://focus.ti.com/lit/ug/swcu050g/swcu050g.pdf
