C programming,

Program Structure for Arduino:

float ReadTemperature()

Set CS LOW

Read two bytes over SPI.

Set CS HIGH

convert temperature to Fahrenheit

return temperature

SetUp:

Set CS as an output

Configure SPI hardware

Configure Serial

Loop:

if 1 seconds has passed,

ReadTemperature();

Transmit temperature over Serial

end

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more info

int TempBits = ( SPI.transfer16(0) >> 3 ) & 0x0fff; //Shift over 3, then mask off upper bits

float Temperature = 0.25 * ( float ) TempBits; // Convert to degrees Celsius

float Temperature = 1.8*Temperature + 32.0; // Convert to degrees Fahrenheit.

In many applications, a separate hardware device will be used to perform a special function. In order to work with this device, some type of communication protocol is needed to move data from the device to the microprocessor. We have already been using a protocol (RS-232), when we send serial data from the Arduino to the Serial Monitor. When communicating with small electronic devices, a more common protocol, known as Serial Peripheral Interface (SPI). The SPI protocol is a three wire interface with a Serial ClocK (SCK), a Master In-Slave Out (MISO) and a Master-Out Slave-In (MOSI) line. The layout of these signals are shown in Figure 7-1, and the names are very descriptive of their function. With all the different devices, the hardware on most microprocessors is built to support a variety of clocking schemes. The various clocking schemes are shown in Figure 7-2. SCLKslave MOSI MISO Master Figure 7-1. Signals for SPI Interface. In the lab, a set of SPI based thermocouples are available which will read the temperature and report it over an SPI interface. Figure 7-3, shows the clocking of the data from the thermocouple. Note this will correspond with the settings of CPOL = 0 and CPHA = 0 (MODE 0-See table 7-1). Now the question is what should the timing of SCK be? In other words, how do we make the system not toggle the clock to quickly? In many applications, a separate hardware device will be used to perform a special function. In order to work with this device, some type of communication protocol is needed to move data from the device to the microprocessor. We have already been using a protocol (RS-232), when we send serial data from the Arduino to the Serial Monitor. When communicating with small electronic devices, a more common protocol, known as Serial Peripheral Interface (SPI). The SPI protocol is a three wire interface with a Serial ClocK (SCK), a Master In-Slave Out (MISO) and a Master-Out Slave-In (MOSI) line. The layout of these signals are shown in Figure 7-1, and the names are very descriptive of their function. With all the different devices, the hardware on most microprocessors is built to support a variety of clocking schemes. The various clocking schemes are shown in Figure 7-2. SCLKslave MOSI MISO Master Figure 7-1. Signals for SPI Interface. In the lab, a set of SPI based thermocouples are available which will read the temperature and report it over an SPI interface. Figure 7-3, shows the clocking of the data from the thermocouple. Note this will correspond with the settings of CPOL = 0 and CPHA = 0 (MODE 0-See table 7-1). Now the question is what should the timing of SCK be? In other words, how do we make the system not toggle the clock to quickly