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I am trying to interface with a mouse sensor and am not able to get data back. datasheet link I have it still soldered to the original PCB but have cut the traces to pins 1-4,6,7 (NCS [SS], MISO, SCLK, MOSI, RESET, NPD [power down {set to 3.3v}])

PLEASE LET ME KNOW IF ANYTHING SEEMS WRONG HERE.

According to the Datasheet, by default the sensor is setup with the pull-up resistors enabled [pg. 29] which enables the open-drain, allowing me to directly connect NCS,MISO,SCLK,MOSI directly to the 5v microcontroller [pg. 15]. This also requires the SPI speed set to 500khz [pg. 10]. RESET is in a (10k)(10k+10k) resistor bridge.

SPI should be set to Mode3 as SCLK is normally high and data should be captured on the rising edge of the clock pulse [pg. 16]

Here is my code:

#include <SPI.h>
const int MOUSEVERSION = 0x00; //mouse version
const int CSmouse = 10;
const int mouseReset = 2;
char val;

void setup() {
  Serial.begin(9600);
  SPI.beginTransaction(SPISettings(500000, MSBFIRST, SPI_MODE3));
  pinMode(CSmouse, OUTPUT);
  pinMode(mouseReset, OUTPUT);
  digitalWrite(CSmouse, HIGH);
  //pull reset pin high for a half second to make sure mouse is ready to go after powering on [pg. 22]
  digitalWrite(mouseReset, HIGH);
  Serial.println("setup");
  delay(500); //half a second
  digitalWrite(mouseReset, LOW);
  Serial.println("end setup");
}

void loop() {
  Serial.println("Start loop");
  digitalWrite(CSmouse, LOW); //CS enable
  SPI.transfer(MOUSEVERSION); //0x00 = read register Product_ID, should reply 0x17
  delayMicroseconds(75);
  Serial.println(SPI.transfer(0)); //actually just gives 0
  delay(500);
}
0

You have SPI.beginTransaction but no SPI.begin().

SPI.begin() is needed to initialize the SPI hardware.

More details about SPI at SPI - Serial Peripheral Interface - for Arduino.

  • Thank you! I was under the impression that beginTransaction() superseded begin() since setClockDivider() and the like were depreciated. That is what I get for assuming. – user2497991 Sep 8 '15 at 4:39

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