This has been tested with 128D EVB SPI connection is shown as following D3 -> 128D EVB pin 82 D4 -> 128D EVB pin 12 D5 -> 128D EVB pin 39

Revision:
0:01dbd5035212
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Mon Nov 06 06:07:02 2017 +0000
@@ -0,0 +1,36 @@
+#include "mbed.h"
+ 
+SPI spi(D3, D4, D5); // mosi, miso, sclk
+DigitalOut cs(D2);
+ 
+int main() {
+    // Chip must be deselected
+    cs = 1;
+ 
+    // Setup the spi for 8 bit data, high steady state clock,
+    // second edge capture, with a 1MHz clock rate
+    spi.format(8,3);
+    spi.frequency(1000000);
+
+    printf("Start application \r\n");   
+    // Select the device by seting chip select low
+    cs = 0;
+ 
+    spi.write(0x5);
+    spi.write(0x20);
+    spi.write(0x00);
+    spi.write('A');
+    spi.write('B');
+    spi.write('C');
+    
+    spi.write(0xFF);
+    spi.write(0xFE);
+    spi.write(0xFD);
+    spi.write(0xFC);
+          
+    wait_ms(100);
+
+    // Deselect the device
+    cs = 1;
+    printf("End of application \r\n");    
+}
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