updated pictures, added arduino example

README.md

@@ -1,6 +1,8 @@
 # exixe: Low-cost miniature Nixie tube driver modules
 
-![Alt text](https://i.imgur.com/JjhNDUQ.jpg)
+![Alt text](resources/title.jpg)
+
+![Alt text](resources/breadboard.jpg)
 
 exixe is a miniature driver module for IN-12 and IN-14 Nixie tubes.
 

exixe_arduino_example/exixe_arduino_example.ino

@@ -0,0 +1,34 @@
+#include <SPI.h>
+#define SPI_BUF_SIZE 16
+
+uint8_t spi_buf[SPI_BUF_SIZE];
+const int slaveSelectPin = 10;
+
+void setup()
+{
+  pinMode(slaveSelectPin, OUTPUT);
+  digitalWrite(slaveSelectPin, HIGH);
+
+  SPI.begin();
+  // 8MHz SCLK, MSB first, SPI mode 0
+  SPI.beginTransaction(SPISettings(8000000, MSBFIRST, SPI_MODE0));
+
+  spi_buf[0] = 0xaa; // first byte, header
+  spi_buf[4] = 0x80 | 127; // digit 4 full brightness
+  spi_buf[13] = 0x80 | 127; // red LED full brightness
+  spi_buf[14] = 0x80 | 28; // green LED brightness 28
+  spi_buf[15] = 0x80 | 0; // blue LED fully off
+}
+
+void loop()
+{
+  // cs low
+  digitalWrite(slaveSelectPin, LOW);
+  // send 16 byte command
+  for (int i = 0; i < SPI_BUF_SIZE; ++i)
+    SPI.transfer(spi_buf[i]);
+  // cs high
+  digitalWrite(slaveSelectPin, HIGH);
+
+  delay(200);
+}