Timo Karppinen / Mbed OS McLab13_Sensor_SPI_PmodALS_OS6

The code is developed for the hardware NUCLEO-L432KC or any other board with SPI communication and the Digilent Pmod ALS1 ambient light sensor module. The purpose is to make students to understand the development process. They need to study the original analog to digital converter documentation to understand how the converter 16 bit output is converted to an illuminance value.

Files at this revision

API Documentation at this revision

Revision 1:d1f1c7d9fbba, committed 2022-01-09

Comitter:
timo_k2
Date:
Sun Jan 09 19:55:59 2022 +0000
Parent:
0:f8565ce9a7ca
Commit message:
2 MHz SPI clock frequency for the ADC chip.

Changed in this revision

main.cpp Show annotated file Show diff for this revision Revisions of this file 
--- a/main.cpp	Tue Sep 14 11:33:44 2021 +0000
+++ b/main.cpp	Sun Jan 09 19:55:59 2022 +0000
@@ -58,9 +58,10 @@
         // Setup the spi for 8 bit data, high steady state clock,
         // second edge capture, with a 12MHz clock rate
         spi.format(8,0);           
-        spi.frequency(12000000);
+        spi.frequency(2000000); //  1 to 4 MHz recommend for the adc081s021
         // ready to wait the conversion start
         alsCS.write(1);
+        ThisThread::sleep_for(1ms);
 
     while (true) {
      if(sw2.read() == 0){
@@ -95,11 +96,13 @@
     
     // Begin the conversion process and serial data output
     alsCS.write(0); 
+    ThisThread::sleep_for(1ms);
     // Reading two 8bit bytes by writing two dymmy 8bit bytes
     alsByte0 = spi.write(0x00);
     alsByte1 = spi.write(0x00);
     // End of serial data output and back to tracking mode
     alsCS.write(1);
+    ThisThread::sleep_for(1ms);
     // Check the http://www.ti.com/lit/ds/symlink/adc081s021.pdf
     // The data looks like 0000AAAA AAAA0000 on the alsByte0 alsByte1
     printf("alsByte0 alsByte1 in hexadecimal %X %X\r\n",alsByte0, alsByte1);