The DC/DC converter for the LCD baclight

Close-up of screen in 160x120 mode . Notice top and bottom lines of the dispay are not used. ( not cleared , from a previous picture in 128x128 mode.

Setup with 3310 LCD , 6610 LCD & Memsic C62020M +-2g sensor in the middle back. All of this with a 2x16 lcd and a 3x12 I2C ( ex GH688 ) LCD with the C328 and SD flash disk is connected to the AVR-CF pcb. SD Flash disk socket is mounted behind 6610 LCD

The main use of the AVR-CF pcb is to hook up a C328 camera and snap and save the picture in JPG format. This works well but the problem is that if you have pc available you can set the camera and take a few shots and view it on the screen to check the focus and actual field of view. This is a bit of a pain in the field. There is a simple solution for this problem , thanks to the 132x132 dot colour screen used in the Nokia 6610. Although it is possible to decode a JPG file for display , I have not tried it on a AVR jet, the camera can also provide the picture in a RAW 4 ,8,12,16 bit format. What is more is that the picture size can be selected in the camera. This helps a lot so the only real work is to hook up the LCD and to get the data flow from the camera to the LCD.

The LCD is connected as a "SPI " slave with the MOSI and SCLK lines , a /RESET and /CE is also required . If you want to control the BACKLIGHT leds , an extra io line is also required. Some of the LCD 's need +- 3.3v for the BL and others +- 6.5 v . ( Add a 50 R reseistor and start with a low voltage ) I use a 3.3v to 6.7v step-up circuit with a LTC 1613 . The advantage is that you can set the output voltage on this model and it also has a /shut-down mode . It might also be better to go for the Phillips type display. It has the row of large pads to solder wires direct to the flex pcb. Pin 1 is closet to the smd connector. Only the first 10 solder pads are used and pad 7 is a N/C . Please note 3.3 Vdd MAX - Do not make a mistake and burn your LCD!!!

At this stage I use the colour display only as a "viewfinder" , no text or plot routines . Not even a " clear screen " command .

The LCD start up in 12 bit RGB mode after a reset, so only the voltage boost circuit and a few other commands are needed afer a reset.

The C328 can dump the picture data at a max serial speed of 115200bps . At 640x480 ( best quality picture ) and at 12 bits it take about (((640x480x(3/2) ) * 10 ) / 115200 ) seconds = +- 40 sec ( 3/2 for the 12 bits per pixel and the 10 for 8 bits + 1start + 1 stop for the serial data )

Not much of a viewfinder you might say. Yes but we do not need the best picture quality form the camera to see where it is pointing. The camera can snap and then send a 128 x 128 dot x 12 bit file for display. That works out at +- 2.1 sec per frame. Now that is better . The next frame size is 160x120 . To display this size picture , a few pixels on both sides are not displayed and also 6 lines on the top and bottom of the LCD are not used. The centre of the camera is the centre of the LCD. To focus the camera you need better image quality. The next image size from the camere is then 320x240. From that only the centre 132 x 132 dots are on the LCD . The image quality is very good but it now take about 10 seconds per frame. This mode is only used for fine focus setup. So you have fast mode for camera position setup and a slow mode for fine focus setup.

If the picture is saved to the CF disk , you can also display it from the disk to the LCD , only RAW mode files.

Here are a few pictures of the setup. For more info please contact me at nicof@axxess.co.za

















































Other AVR based projects & info.

COLOUR VIEWFINDER for C328 Camera



Closeup of I2c output +-2g angle sensor ( 5x5mm)

Close-up of screen of 320x240 picture display mode