Reduced SPI speed for Expander Pi

Reduce the speed of the SPI bus to improve ADC accuracy.

Author: abelectronicsuk

ExpanderPi/ABE_ExpanderPi.cpp

@@ -38,7 +38,7 @@ apt-get install libi2c-dev
 #define IOADDRESS 0x20
 #define IODIRA 0x00 // IO direction A - 1= input 0 = output
 #define IODIRB 0x01 // IO direction B - 1= input 0 = output
-#define IPOLA 0x02 // Input polarity A 
+#define IPOLA 0x02 // Input polarity A
 #define IPOLB 0x03 // Input polarity B
 #define GPINTENA 0x04 // The GPINTEN register controls the interrupt-onchange feature for each pin on port A.
 #define GPINTENB 0x05 // The GPINTEN register controls the interrupt-onchange feature for each pin on port B.
@@ -80,7 +80,7 @@ using namespace ABElectronics_CPP_Libraries;
 ExpanderPi::ExpanderPi(){
 // SPI Bus Variables
 mode = SPI_MODE_0; // SPI_MODE_0
-speed = 2500000; // SPI bus speed
+speed = 200000; // SPI bus speed
 
 // ADC Variables
 
@@ -174,11 +174,11 @@ int ExpanderPi::adc_read_raw(int channel, int mode) {
 struct spi_ioc_transfer spi;
 memset(&spi,0,sizeof(spi));
 
-spi.tx_buf = (unsigned long)adctx;
+spi.tx_buf = (unsigned long)adctx;
 spi.rx_buf = (unsigned long)adcrx;
 spi.len = 3;
 spi.speed_hz = 1800000; // 1.8MHz Clock Speed
-spi.delay_usecs = 0;
+spi.delay_usecs = 0;
 spi.bits_per_word = 8;
 
 
@@ -254,7 +254,7 @@ void ExpanderPi::dac_set_raw(uint16_t raw, int channel, int gain) {
 tr.rx_buf = (unsigned long)NULL;
 tr.len = 2;
 tr.speed_hz = 20000000; // 20MHz clock speed
-tr.delay_usecs = 0;
+tr.delay_usecs = 0;
 tr.bits_per_word = 8;
 tr.cs_change = 0;
 
@@ -277,7 +277,7 @@ void ExpanderPi::dac_set_voltage(double voltage, int channel, int gain) {
 if (gain == 2) {
 dacvoltage = 4.096;
 }
-
+
 if ((voltage >= 0.0) && (voltage < dacvoltage)) {
 uint16_t rawval = ((voltage / 2.048) * 4096) / gain;
 dac_set_raw(rawval, channel, gain);
@@ -850,7 +850,7 @@ unsigned char *ExpanderPi::rtc_read_memory(unsigned char address, int length) {
 else {
 throw std::out_of_range("address out of range");
 return NULL;
-}
+}
 }
 
 /*===================RTC Methods End ===================*/