void sub_adc_measurement(ot_int* buffer) {
/// This is a blocking ADC capture routine. It should run in 50us or less.
/// 1. Universal ADC config
/// <LI> Reset REFMSTR, REFVSEL_1 = 2.0V </LI>
/// <LI> Voltage Tsample > 1.2us, Temp Tsample > 30us, so use ADCCLK/32
/// for Voltage, ADCCLK/768 for Temp.</LI>
/// <LI> Also in ADCCTL0, use multisample mode, use REF=2.0V </LI>
/// <LI> Use MEM7 (Temp) & MEM8 (Volt), Use internal sampling timer, use MODCLK </LI>
/// <LI> Use 12 bit mode, use fast mode </LI>
/// <LI> MEM7 is Temp, MEM8 is Volt </LI>
REFCTL0 = REFMSTR + REFON + REFVSEL_1;
ADC12CTL0 = 0;
ADC12CTL0 = ADC12SHT1_3 + ADC12SHT0_7 + ADC12MSC + ADC12REFON + ADC12ON;
ADC12CTL1 = ADC12CSTARTADD_7 + ADC12SHP + ADC12CONSEQ_1;
ADC12CTL2 = ADC12RES_2;
ADC12MCTL7 = ADC12SREF_1 + ADC12INCH_10;
ADC12MCTL8 = ADC12SREF_1 + ADC12INCH_11 + ADC12EOS;
/// 2. Start ADC and Wait for ADC to finish. Wait 75us for REF.
/// Grab the data, then kill everything
platform_swdelay_us(75);
ADC12CTL0 |= ADC12ENC;
ADC12CTL0 |= ADC12SC;
while ((ADC12CTL1 & ADC12BUSY) == ADC12BUSY);
ADC12CTL0 &= ~(ADC12ENC | ADC12SC);
ADC12CTL0 &= ~(ADC12ON + ADC12REFON);
REFCTL0 &= ~(REFMSTR + REFON + REFGENACT);
/// 3. Convert Temperature:
///@todo Build a Fixed-Point Model instead of this heavy floating point one.
///
/// This temperature conversion method pulls device-specific calibration
/// data from the TLV space and uses it to produce a linear model to map
/// the acquired ADC value.
{
float val_dC;
val_dC = tmodel.slope_dC*(float)ADC12MEM7 + tmodel.offset_dC;
buffer[0] = (ot_int)val_dC;
}
/// 4. Convert Voltage:
/// Vdd is acquired as 12 bit number representing Vdd/2 in 1/4095V units.
/// x(V) = 4095*(Vdd/2)/1.93V; x(mV) = (4095/2*1930mV)Vdd ~= Vdd
//buffer[1] = volt; // Cheap way, not accurate
buffer[1] = (ot_int)((float)ADC12MEM8 * (3860.f/4095.f)); // Higher accuracy method
}
void sub_adc_measurement(ot_int* buffer) {
/// This is a blocking ADC capture routine. It should take about 1.6 ms.
/// @todo change the algorithm to fixed-point.
float scratch;
ADC12CTL0 = 0;
// Reset REFMSTR to hand over control to: REFVSEL_1 = 2.0V, ADC12_A ref control registers
REFCTL0 = REFMSTR + REFON + REFVSEL_1;
ADC12CTL0 = ADC12SHT1_12 + ADC12SHT0_12 + ADC12REFON + ADC12ON + ADC12MSC;
ADC12CTL1 = ADC12SHP + ADC12CONSEQ_1; // enable sample timer
ADC12CTL2 = ADC12RES_2 + ADC12SR; // 12-bit mode, 50ksps
ADC12MCTL0 = ADC12SREF_1 + ADC12INCH_10;
ADC12MCTL1 = ADC12SREF_1 + ADC12INCH_11 + ADC12EOS;
// REFO is supposed to startup in 25us...
platform_swdelay_us(25);
// Start conversion
ADC12CTL0 |= ADC12ENC;
ADC12CTL0 |= ADC12SC;
while ((ADC12CTL1 & ADC12BUSY) == ADC12BUSY);
///@note I think floats are bad, but at the moment I don't care to untangle
/// this knot into fixed-point (same goes for below)
scratch = (float)ADC12MEM1;
scratch = ((scratch * 2.0f / 4095) * 2 * 1000 - 100);
buffer[0] = (ot_int)scratch;
scratch = (float)ADC12MEM0;
scratch = ((scratch * 2.0f / 4095) * 100);
scratch = scratch*24.0f/725*100;
buffer[1] = (ot_int)scratch;
// Shut everything down
ADC12CTL0 &= ~(ADC12ENC | ADC12SC);
ADC12CTL0 &= ~(ADC12ON + ADC12REFON);
REFCTL0 &= ~(REFMSTR + REFVSEL_2 + REFON + REFGENACT);
}
