I just finished Bert van Dam's book ARM7 part 1 and want to continue with the connection of a textLCD (H160204C YF621).  I connected all the wires according to the instructions and use an external 5V power supply. Then loaded the textLCD library into the compiler and used the main program "textLCD_helloworld" and loaded it after compilation. Nothing was to see on the display. As I did not see any pin definitions in the TextLCD.h file I added to the input file ...DigitalIn d4(p17)... and similarly for all other input pins. To be sure that it was my program that runned I added a light effect with the LED1 ... LED4. After compilation, loading and reset I see only the light effect but nothing on the display. As I don't even see background ligth (with LCDpin 15 high via 180 Ohm) I don't trust the display. Does anyone see an error in the procedure?

It turnes out that the textLCD display works fine at 4.98 V and does not work at 4.37 V. Problem solved.