Hi I am using the example code for reading the internal temperature and I am getting nonsense results. The steady state temperature in degrees C is 55C ( It should be ~room temperature). Heating the chip causes the degrees C to drop not rise which I cannot explain especially as the raw ADC values are increasing.
The code I am using is from the resource explorer and repeated below.
Question - are the memory address values for #define CALADC_15V_30C(0x1A1A) and #define CALADC_15V_85C(0x1A1C) correct? The data sheet doesn't have these values exactly as written, I assume the values are CAL_ADC_15T30 and CAL_ADC_15T85 which have memory offset addresses 0x8 and 0xB.
Thanks in advance.
Richard
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//******************************************************************************
// MSP430FR235x Demo - ADC, Sample A12 Temp and Convert to oC and oF
//
// Description: This example works on Single-Channel Single-Conversion Mode.
// A single sample is made on A12 (temperature) with reference to
// internal 1.5V Vref. Software sets ADCSC to start sample and conversion
// periodically
// - ADCSC automatically cleared at EOC. ADC internal oscillator times
// sample and conversion. In Mainloop MSP430 waits in LPM3 to save power until
// ADC conversion complete, ADC12_ISR will convert the result to oC and oF
//
// ACLK = default REFO ~32768Hz, MCLK = SMCLK = default DCODIV ~1MHz.
//
// Uncalibrated temperature measured from device to device will vary due to
// slope and offset variance from device to device - please see datasheet.
//
// This code example show how to use the TLV calibrated data to measure temperature.
// This code example is for industrial temperature device which operating temperature range is -40oC ~ +85oC.
// For extended temperature device (-40oC ~ +105oC), ADC calibration result is for 105oC - please see datasheet.
//
// MSP430FR2355
// -----------------
// /|\| |
// | | |
// --|RST |
// | |
// >---|A12(temp) |
//
//
// Winter Yu
// Texas Instruments Inc.
// April. 2018
// Built with IAR Embedded Workbench v7.10 & Code Composer Studio v7.2
//******************************************************************************
#include <msp430.h>
#define CALADC_15V_30C *((unsigned int *)0x1A1A) // Temperature Sensor Calibration-30 C
// See device datasheet for TLV table memory mapping
#define CALADC_15V_85C *((unsigned int *)0x1A1C) // Temperature Sensor Calibration-High Temperature (85 for Industrial, 105 for Extended)
int main(void)
{
WDTCTL = WDTPW | WDTHOLD; // Stop WDT
TB0CCTL0 |= CCIE; // TBCCR0 interrupt enabled
TB0CCR0 = 65535;
TB0CTL = TBSSEL__ACLK | MC__UP; // ACLK, UP mode
// Configure ADC - Pulse sample mode; ADCSC trigger
ADCCTL0 |= ADCSHT_8 | ADCON; // ADC ON,temperature sample period>30us
ADCCTL1 |= ADCSHP; // s/w trig, single ch/conv, MODOSC
ADCCTL2 &= ~ADCRES; // clear ADCRES in ADCCTL
ADCCTL2 |= ADCRES_2; // 12-bit conversion results
ADCMCTL0 |= ADCSREF_1 | ADCINCH_12; // ADC input ch A12 => temp sense
ADCIE |=ADCIE0; // Enable the Interrupt request for a completed ADC_B conversion
// Configure reference
PMMCTL0_H = PMMPW_H; // Unlock the PMM registers
PMMCTL2 |= INTREFEN | TSENSOREN; // Enable internal reference and temperature sensor
__delay_cycles(400); // Delay for reference settling
__bis_SR_register(LPM0_bits | GIE); // LPM0 with interrupts enabled
__no_operation(); // Only for debugger
}
// ADC interrupt service routine
#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector=ADC_VECTOR
__interrupt void ADC_ISR(void)
#elif defined(__GNUC__)
void __attribute__ ((interrupt(ADC_VECTOR))) ADC_ISR (void)
#else
#error Compiler not supported!
#endif
{
volatile float temp;
volatile float IntDegF;
volatile float IntDegC;
switch(__even_in_range(ADCIV,ADCIV_ADCIFG))
{
case ADCIV_NONE:
break;
case ADCIV_ADCOVIFG:
break;
case ADCIV_ADCTOVIFG:
break;
case ADCIV_ADCHIIFG:
break;
case ADCIV_ADCLOIFG:
break;
case ADCIV_ADCINIFG:
break;
case ADCIV_ADCIFG:
temp = ADCMEM0;
// Temperature in Celsius
// The temperature (Temp, C)=
IntDegC = (temp-CALADC_15V_30C)*(85-30)/(CALADC_15V_85C-CALADC_15V_30C)+30;
// Temperature in Fahrenheit
// Tf = (9/5)*Tc | 32
IntDegF = 9*IntDegC/5+32;
//__bic_SR_register_on_exit(LPM3_bits); // Exit LPM3
break;
default:
break;
}
}
// Timer B0 interrupt service routine
#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector = TIMER0_B0_VECTOR
__interrupt void Timer_B (void)
#elif defined(__GNUC__)
void __attribute__ ((interrupt(TIMER0_B0_VECTOR))) Timer_B (void)
#else
#error Compiler not supported!
#endif
{
ADCCTL0 |= ADCENC | ADCSC; // Sampling and conversion start
}
