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Gigabeat S: Add charge current and battery temp readout in power management and display in the battery screen. Thermistor data was obtained experimentally from one pulled off a dead board and appears basically correct when read back on a working device (which requires letting it settle to ambient temperature - a long wait so not easy to do). Sending me more thermistors would help improve accuracy *fingers crossed that it's close enough*. :-) This commit does NOT add charging but is a step towards implementing it.

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@17626 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Michael Sevakis 2008-05-25 01:38:08 +00:00
parent 11a667b6ca
commit d892214d88
3 changed files with 82 additions and 1 deletions
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14
apps/debug_menu.c
View file

@ -18,6 +18,7 @@
****************************************************************************/
#include "config.h"
#include <stdlib.h>
#include <stdio.h>
#include <stdbool.h>
#include <string.h>
@ -1649,7 +1650,18 @@ static bool view_battery(void)
snprintf(buf, 30, "Charger: %s",
charger_inserted() ? "present" : "absent");
lcd_puts(0, 3, buf);
#endif
#if defined TOSHIBA_GIGABEAT_S
y = battery_adc_charge_current();
x = y < 0 ? '-' : ' ';
y = abs(y);
snprintf(buf, 30, "I Charge:%c%d.%03d A", (char)x, y / 1000, y % 1000);
lcd_puts(0, 4, buf);
y = battery_adc_temp();
snprintf(buf, 30, "T Battery: %dC (%dF)", y, (9*y + 160) / 5);
lcd_puts(0, 5, buf);
#endif /* defined TOSHIBA_GIGABEAT_S */
#endif /* defined IPOD_NANO || defined IPOD_VIDEO */
#endif /* CONFIG_CHARGING != CHARGING_CONTROL */
#endif /* CONFIG_CHARGING */
break;

2
firmware/target/arm/imx31/gigabeat-s/adc-target.h
View file

@ -45,5 +45,7 @@
#define ADC_READ_ERROR 0xFFFF
void adc_done(void);
int battery_adc_charge_current(void);
unsigned int battery_adc_temp(void);
#endif

67
firmware/target/arm/imx31/gigabeat-s/powermgmt-imx31.c
View file

@ -24,6 +24,37 @@
#include "adc.h"
#include "powermgmt.h"
/**
* Fixed-point natural log
* taken from http://www.quinapalus.com/efunc.html
* "The code assumes integers are at least 32 bits long. The (positive)
* argument and the result of the function are both expressed as fixed-point
* values with 16 fractional bits, although intermediates are kept with 28
* bits of precision to avoid loss of accuracy during shifts."
*/
static long flog(int x)
{
long t,y;
y=0xa65af;
if(x<0x00008000) x<<=16, y-=0xb1721;
if(x<0x00800000) x<<= 8, y-=0x58b91;
if(x<0x08000000) x<<= 4, y-=0x2c5c8;
if(x<0x20000000) x<<= 2, y-=0x162e4;
if(x<0x40000000) x<<= 1, y-=0x0b172;
t=x+(x>>1); if((t&0x80000000)==0) x=t,y-=0x067cd;
t=x+(x>>2); if((t&0x80000000)==0) x=t,y-=0x03920;
t=x+(x>>3); if((t&0x80000000)==0) x=t,y-=0x01e27;
t=x+(x>>4); if((t&0x80000000)==0) x=t,y-=0x00f85;
t=x+(x>>5); if((t&0x80000000)==0) x=t,y-=0x007e1;
t=x+(x>>6); if((t&0x80000000)==0) x=t,y-=0x003f8;
t=x+(x>>7); if((t&0x80000000)==0) x=t,y-=0x001fe;
x=0x80000000-x;
y-=x>>15;
return y;
}
const unsigned short battery_level_dangerous[BATTERY_TYPES_COUNT] =
{
3450
@ -55,3 +86,39 @@ unsigned int battery_adc_voltage(void)
return ((adc_read(ADC_BATTERY) * 2303) >> 10) + 2400;
}
/* Returns battery charge current from ADC [milliamps] */
int battery_adc_charge_current(void)
{
/* Positive reading = charger to battery
* Negative reading = battery to charger terminal
* ADC reading -512-511 = -2875mA-2875mA */
unsigned int value = adc_read(ADC_CHARGER_CURRENT);
return (((int)value << 22) >> 22) * 2881 >> 9;
}
/* Returns battery temperature from ADC [deg-C] */
unsigned int battery_adc_temp(void)
{
unsigned int value = adc_read(ADC_BATTERY_TEMP);
/* E[volts] = value * 2.3V / 1023
* R[ohms] = E/I = E[volts] / 0.00002[A] (Thermistor bias current source)
*
* Steinhart-Hart thermistor equation (sans "C*ln^2(R)" term because it
* has negligible effect):
* [A + B*ln(R) + D*ln^3(R)] - 273.15 = 1 / T[°K]
*
* Coeffients that fit experimental data (one thermistor so far, one run):
* A = 0.0013002631685462800
* B = 0.0002000841932612330
* D = 0.0000000640446750919
*
* Fixed-point output matches the floating-point version for each ADC
* value.
*/
int R = 2070000 * value;
long long ln = flog(R) + 83196;
long long t0 = 425890304133ll;
long long t1 = 1000000*ln;
long long t3 = ln*ln*ln / 13418057;
return ((32754211579494400ll / (t0 + t1 + t3)) - 27315) / 100;
}