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Created by Dtynin on 9/27/2024 in #firmware-and-baremetal
How to Expand 10-Bit ADC Signal for 16-Bit SPI Communication Between Two Arduino Unos
To transmit a 10-bit signal from one Arduino to another using SPI, you need to expand the 10-bit signal to fit into a 16-bit frame. Signal Expansion - Pack the 10-bit Signal: Shift the 10-bit value left by 6 bits to create space for padding. 
   uint16_t expandedSignal = (x << 6);
   
   uint16_t expandedSignal = (x << 6);
- Split for Transmission: Extract the high and low bytes. 
   byte highByte = (expandedSignal >> 8) & 0xFF;
   byte lowByte = expandedSignal & 0xFF;
   
   byte highByte = (expandedSignal >> 8) & 0xFF;
   byte lowByte = expandedSignal & 0xFF;
Updated Master Code Send the two bytes: 
digitalWrite(SS, LOW);
SPI.transfer(highByte);
SPI.transfer(lowByte);
digitalWrite(SS, HIGH);
digitalWrite(SS, LOW);
SPI.transfer(highByte);
SPI.transfer(lowByte);
digitalWrite(SS, HIGH);
Reconstruct the original signal: 
uint16_t receivedSignal = (receivedHighByte << 8) | receivedLowByte;
uint16_t originalSignal = receivedSignal >> 6; // Retrieve the original 10-bit signal
uint16_t receivedSignal = (receivedHighByte << 8) | receivedLowByte;
uint16_t originalSignal = receivedSignal >> 6; // Retrieve the original 10-bit signal
Testing Without a Second Arduino You can simulate SPI by connecting the MOSI pin of the master to the MISO pin of the slave, allowing for loopback testing. - Ensure correct connections (MOSI, MISO, SCK, SS). - Pay attention to timing with appropriate delays. - Consider pull-up resistors for the SS line. - Use serial prints for debugging data transmission.
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