diff options
Diffstat (limited to 'firmware/target/arm/imx31/gigabeat-s')
| -rw-r--r-- | firmware/target/arm/imx31/gigabeat-s/powermgmt-imx31.c | 86 |
1 files changed, 44 insertions, 42 deletions
diff --git a/firmware/target/arm/imx31/gigabeat-s/powermgmt-imx31.c b/firmware/target/arm/imx31/gigabeat-s/powermgmt-imx31.c index b4a6c61fbb..e563fede43 100644 --- a/firmware/target/arm/imx31/gigabeat-s/powermgmt-imx31.c +++ b/firmware/target/arm/imx31/gigabeat-s/powermgmt-imx31.c @@ -53,36 +53,6 @@ const unsigned short percent_to_volt_charge[11] = 3480, 3550, 3590, 3610, 3630, 3650, 3700, 3760, 3800, 3910, 3990 }; -/** - * 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; -} - /* Returns battery voltage from ADC [millivolts] */ unsigned int battery_adc_voltage(void) { @@ -134,30 +104,62 @@ unsigned int cccv_regulator_dissipation(void) /* Returns battery temperature from ADC [deg-C] */ 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): + * Steinhart-Hart thermistor equation: * [A + B*ln(R) + D*ln^3(R)] = 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. */ + static const unsigned short ntc_table[] = + { +#if 0 /* These have degree deltas > 1 (except the final two) so leave them + * out. 70 deg C upper limit is quite sufficient. */ + 0, /* INF */ 1, /* 171 */ 2, /* 145 */ 3, /* 130 */ + 4, /* 121 */ 5, /* 114 */ 6, /* 108 */ 7, /* 104 */ + 8, /* 100 */ 9, /* 96 */ 10, /* 93 */ 11, /* 91 */ + 12, /* 88 */ 13, /* 86 */ 14, /* 84 */ 15, /* 82 */ + 16, /* 81 */ 17, /* 79 */ 18, /* 78 */ 19, /* 76 */ + 20, /* 75 */ 21, /* 74 */ 22, /* 72 */ 23, /* 71 */ +#endif + 24, /* 70 */ 25, /* 69 */ 26, /* 68 */ 27, /* 67 */ + 28, /* 66 */ 30, /* 65 */ 31, /* 64 */ 32, /* 63 */ + 33, /* 62 */ 35, /* 61 */ 36, /* 60 */ 38, /* 59 */ + 39, /* 58 */ 41, /* 57 */ 43, /* 56 */ 45, /* 55 */ + 47, /* 54 */ 49, /* 53 */ 51, /* 52 */ 53, /* 51 */ + 56, /* 50 */ 58, /* 49 */ 61, /* 48 */ 63, /* 47 */ + 66, /* 46 */ 69, /* 45 */ 73, /* 44 */ 76, /* 43 */ + 80, /* 42 */ 83, /* 41 */ 87, /* 40 */ 92, /* 39 */ + 96, /* 38 */ 101, /* 37 */ 106, /* 36 */ 111, /* 35 */ + 116, /* 34 */ 122, /* 33 */ 128, /* 32 */ 135, /* 31 */ + 142, /* 30 */ 149, /* 29 */ 156, /* 28 */ 164, /* 27 */ + 173, /* 26 */ 182, /* 25 */ 192, /* 24 */ 202, /* 23 */ + 212, /* 22 */ 224, /* 21 */ 236, /* 20 */ 249, /* 19 */ + 262, /* 18 */ 277, /* 17 */ 292, /* 16 */ 308, /* 15 */ + 325, /* 14 */ 344, /* 13 */ 363, /* 12 */ 384, /* 11 */ + 406, /* 10 */ 429, /* 9 */ 454, /* 8 */ 480, /* 7 */ + 509, /* 6 */ 539, /* 5 */ 571, /* 4 */ 605, /* 3 */ + 641, /* 2 */ 680, /* 1 */ 722, /* 0 */ 766, /* -1 */ + 813, /* -2 */ 864, /* -3 */ 918, /* -4 */ 976, /* -5 */ + }; + + unsigned int value = adc_read(ADC_BATTERY_TEMP); + if (value > 0) { - 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; + unsigned i; + + for (i = 1; i < ARRAYLEN(ntc_table); i++) + { + if (ntc_table[i] > value) + break; + } + + return 71 - i; } return INT_MIN; |