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First attempt at using external clock for Teensy ADC.

This commit is contained in:
Jonathan Naylor 2016-11-15 08:07:24 +00:00
parent dd5940fe2e
commit 59d93b5a6f
1 changed files with 49 additions and 11 deletions
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40
IOTeensy.cpp
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@ -50,6 +50,21 @@ extern "C" {
io.interrupt(1U);
}
#endif
#if defined(EXTERNAL_OSC)
void ftm0_isr()
{
FTM0_CNT = 0; // Reset count value
if ((FTM0_SC & FTM_SC_TOF) == FTM_SC_TOF) // Read the timer overflow flag (TOF in FTM0_SC)
FTM0_SC &= ~FTM_SC_TOF; // If set, clear overflow flag
// Kick off the ADCs with interrupt at the end of conversion
ADC0_SC1A = ADC_SC1_AIEN | PIN_ADC;
#if defined(SEND_RSSI_DATA)
ADC1_SC1A = ADC_SC1_AIEN | PIN_RSSI;
#endif
}
#endif
}
void CIO::initInt()
@ -84,7 +99,11 @@ void CIO::startInt()
ADC0_CFG1 = ADC_CFG1_ADIV(1) | ADC_CFG1_ADICLK(1) | ADC_CFG1_MODE(1) |
ADC_CFG1_ADLSMP; // Single-ended 12 bits, long sample time
ADC0_CFG2 = ADC_CFG2_MUXSEL | ADC_CFG2_ADLSTS(2); // Select channels ADxxxb
#if defined(EXTERNAL_OSC)
ADC0_SC2 = ADC_SC2_REFSEL(1); // Voltage ref internal, software trigger
#else
ADC0_SC2 = ADC_SC2_REFSEL(1) | ADC_SC2_ADTRG; // Voltage ref internal, hardware trigger
#endif
ADC0_SC3 = ADC_SC3_CAL | ADC_SC3_AVGE | ADC_SC3_AVGS(0); // Enable averaging, 4 samples
while ((ADC0_SC3 & ADC_SC3_CAL) == ADC_SC3_CAL) // Wait for calibration
@ -94,7 +113,10 @@ void CIO::startInt()
sum0 = (sum0 / 2U) | 0x8000U;
ADC0_PG = sum0;
#if !defined(EXTERNAL_OSC)
ADC0_SC1A = ADC_SC1_AIEN | PIN_ADC; // Enable ADC interrupt, use A0
#endif
NVIC_ENABLE_IRQ(IRQ_ADC0);
#if defined(SEND_RSSI_DATA)
@ -103,7 +125,11 @@ void CIO::startInt()
ADC1_CFG1 = ADC_CFG1_ADIV(1) | ADC_CFG1_ADICLK(1) | ADC_CFG1_MODE(1) |
ADC_CFG1_ADLSMP; // Single-ended 12 bits, long sample time
ADC1_CFG2 = ADC_CFG2_MUXSEL | ADC_CFG2_ADLSTS(2); // Select channels ADxxxb
#if defined(EXTERNAL_OSC)
ADC1_SC2 = ADC_SC2_REFSEL(1); // Voltage ref internal, software trigger
#else
ADC1_SC2 = ADC_SC2_REFSEL(1) | ADC_SC2_ADTRG; // Voltage ref internal, hardware trigger
#endif
ADC1_SC3 = ADC_SC3_CAL | ADC_SC3_AVGE | ADC_SC3_AVGS(0); // Enable averaging, 4 samples
while ((ADC1_SC3 & ADC_SC3_CAL) == ADC_SC3_CAL) // Wait for calibration
@ -113,10 +139,22 @@ void CIO::startInt()
sum1 = (sum1 / 2U) | 0x8000U;
ADC1_PG = sum1;
#if !defined(EXTERNAL_OSC)
ADC1_SC1A = ADC_SC1_AIEN | PIN_RSSI; // Enable ADC interrupt, use A2
#endif
NVIC_ENABLE_IRQ(IRQ_ADC1);
#endif
#if defined(EXTERNAL_OSC)
// Set up for an external oscillator input
SIM_SCGC6 |= SIM_SCGC6_FTM0;
FTM0_MODE = FTM_MODE_WPDIS | FTM_MODE_FTMEN;
FTM0_MOD = EXTERNAL_OSC / 24000;
FTM0_CNTIN = 0;
FTM0_SC = FTM_SC_TOIE | FTM_SC_CLKS(3); // External clock, overflow interrupts, no prescaling
NVIC_ENABLE_IRQ(IRQ_FTM0);
#else
// Setup PDB for ADC0 (and ADC1) at 24 kHz
SIM_SCGC6 |= SIM_SCGC6_PDB; // Enable PDB clock
PDB0_MOD = F_BUS / 24000; // Timer period
@ -128,7 +166,7 @@ void CIO::startInt()
PDB0_SC = PDB_SC_TRGSEL(15) | PDB_SC_PDBEN | // SW trigger, enable interrupts, continuous mode
PDB_SC_PDBIE | PDB_SC_CONT | PDB_SC_LDOK; // No prescaling
PDB0_SC |= PDB_SC_SWTRIG; // Software trigger (reset and restart counter)
NVIC_ENABLE_IRQ(IRQ_PDB);
#endif
// Initialise the DAC
SIM_SCGC2 |= SIM_SCGC2_DAC0;