M
mkstevo
Guest
Inspired by the sterling efforts of Nick12ab in getting his VFD displays operating, I dug out a display sent to me as a sample by Noritake Itron. This is a two line 20 character graphic VFD, similar to a 20x2 LCD graphic display.
Using the code in one of Nick12ab's posts I tried to get the Noritake Itron CU20024 display to work. Whilst it didn't work directly, it did provide me with some insight into how I might get it to work. After my reward of getting it to light up I then modified the program from Ron Hackett's PicAxe for the Evil Genius book for a serial LCD (using a four line parallel interface + control lines) so that it drove the three line SPI interface of the VFD. Using only three lines to drive the VFD and one for serial input means that rather than needing a 14M2 to drive the LCD, the VFD can be driven from an 08M2.
If the 'VFD driver' is programmed with the example from the Zip file (Serial_VFD_08M2.bas) when connected up and powered, it will (should) display on line 1:
Serial VFD V1.0
then on line 2:
Ready.BaudRate N4800
It will then wait until some serial data is transmitted at which point the display will clear and display the transmitted text.
If the serial port for data is held high for five seconds at power up, the VFD driver will start a test mode, where every character in the font set is printed across the lines of the display. On the PCB files provided, there is the option of including a tact push button switch for performing the test mode selection.
I have also included a short demo program (VFD_Serial_test.bas) for a second 08M2 to be used as a 'Master' which has a few short lines of text that are sequentially sent to the display. As it stands, the demo program has most of the routines for displaying text commented out and simply runs a clock program based on the 08M2 internal 'Time' variable. This updates the time display (on line 2) as often as possible, but the top line of the display (line 1) is only transmitted once every five seconds.
I could not get either the commands for moving to a specific position on the display to work as anticipated, nor the brightness control commands. The brightness would 'scroll' through the various levels in sequence each time I called the brightness function, but I couldn't get it to go to a specific brightness function. Moving to a specific position on the screen I got to work but after setting the input position to the right character, the following text was entered 'backwards' (from right to left) and not having much inclination to figure out why, I left this feature out. (Coward!) Therefore, to write to a specific location, the 'Master' control has to create a twenty character line in the correct sequence and then write the entire line. I used the bptr and @bptr commands to do this, and the VFD_Serial_test.bas program uses this technique to assemble the time display.
The attached Zip file includes the two PicAxe basic programs (Serial_VFD_08M2.bas and VFD_Serial_test.bas) the circuit diagram of the VFD serial driver (slave) along with the PCB artwork and the Noritake Itron datasheet for the display. The display I had was set for the International Font which I changed to the Katakana Font by removing the J/*E link on the PCB (see page 14 of the datasheet) this font offers more useful characters such as degrees C and degrees F, musical notes, Ohms, Pi, Pounds, Yen and arrow symbols.
Using the code in one of Nick12ab's posts I tried to get the Noritake Itron CU20024 display to work. Whilst it didn't work directly, it did provide me with some insight into how I might get it to work. After my reward of getting it to light up I then modified the program from Ron Hackett's PicAxe for the Evil Genius book for a serial LCD (using a four line parallel interface + control lines) so that it drove the three line SPI interface of the VFD. Using only three lines to drive the VFD and one for serial input means that rather than needing a 14M2 to drive the LCD, the VFD can be driven from an 08M2.
If the 'VFD driver' is programmed with the example from the Zip file (Serial_VFD_08M2.bas) when connected up and powered, it will (should) display on line 1:
Serial VFD V1.0
then on line 2:
Ready.BaudRate N4800
It will then wait until some serial data is transmitted at which point the display will clear and display the transmitted text.
If the serial port for data is held high for five seconds at power up, the VFD driver will start a test mode, where every character in the font set is printed across the lines of the display. On the PCB files provided, there is the option of including a tact push button switch for performing the test mode selection.
I have also included a short demo program (VFD_Serial_test.bas) for a second 08M2 to be used as a 'Master' which has a few short lines of text that are sequentially sent to the display. As it stands, the demo program has most of the routines for displaying text commented out and simply runs a clock program based on the 08M2 internal 'Time' variable. This updates the time display (on line 2) as often as possible, but the top line of the display (line 1) is only transmitted once every five seconds.
I could not get either the commands for moving to a specific position on the display to work as anticipated, nor the brightness control commands. The brightness would 'scroll' through the various levels in sequence each time I called the brightness function, but I couldn't get it to go to a specific brightness function. Moving to a specific position on the screen I got to work but after setting the input position to the right character, the following text was entered 'backwards' (from right to left) and not having much inclination to figure out why, I left this feature out. (Coward!) Therefore, to write to a specific location, the 'Master' control has to create a twenty character line in the correct sequence and then write the entire line. I used the bptr and @bptr commands to do this, and the VFD_Serial_test.bas program uses this technique to assemble the time display.
The attached Zip file includes the two PicAxe basic programs (Serial_VFD_08M2.bas and VFD_Serial_test.bas) the circuit diagram of the VFD serial driver (slave) along with the PCB artwork and the Noritake Itron datasheet for the display. The display I had was set for the International Font which I changed to the Katakana Font by removing the J/*E link on the PCB (see page 14 of the datasheet) this font offers more useful characters such as degrees C and degrees F, musical notes, Ohms, Pi, Pounds, Yen and arrow symbols.
