8x8 dot matrix display project

[memo]

hi me friends
i want to build project which is PIC 16F877 controls the 6 (8x8) dot matrix display using a driver .
my questions what is suitable driver to drive 6 (8x8) and how can i start to write program for PIC to display scrolling message and right & left arrows.
so i will be grateful for any help

[Mark]

Search the forum and you will find code that I have already posted that does exactly what you want.

[memo]

hi mark
thank you for consideration, but i cant find suitable driver for 8x8 led dot matrix display

[Guest]

I have a PCB and design for a 6 char display using 5x7 matrixes and an 877a if you are interested? Bare PCB would be £30 (4 layer). I have an 877a to chuck in too at £4. Plus full source for smooth scrolling software of course.
Parts cost are an additional approx £25 which I can supply as a kit or you can source yourself. (Be warned, its surface mount, so fiddly!)

For the record it doesn't use a driver chip cos I wanted full control over the pixels.

[John P]

Take a look at the MAX7219:

http://www.maxim-ic.com/quick_view2.cfm/qv_pk/1339

[Guest]

I may be wrong but I don't think you can do smooth scrolling with MAX7219. Scrolling character by character is OK if you have a large (many chars) display but its easier to read a short display if the scrolling is smooth.

[Gizz]

[Mark]

[John P]

Well no, the Maxim chip won't do the scrolling for you. And for 6 characters at 8x8 each, you'd need 6 of the chips. But the interface would be simple, and the software in the PIC not too bad. Whether it's better to represent a horizontal set of 8 pixels as a byte, or a vertical set, I'm not sure. Anyway, either way it comes to 48 bytes, which isn't too alarming.

[Mark]

Well I would just use a shift register.

[memo]

hi my friends again

thank you for response, but how many shift registers can i use for 6(8x8) led dot matrix display and how i can connect shift registers to PIC....... and what is the model of shift register

[Gizz]

There are various SRs (HC595 comes to mind), but (depending on LED type) you can run the sink from an HC373 latch (rows) and then source from a P channel mosfet array or a driver chip (columns). Latch all 6 373's to present the data, light up one column (per display), wait a few ms, and repeat for the next column. This assumes you have 8 data lines to the latches, 6 latch lines, and 8 column strobe lines, = 22 IO lines. Whether you use a latch or a shift reg is immiterial except a SR take slonger to load the data in.

To connect SR to PIC, use tracks on a PCB (!)

[Ttelmah]

For a slightly similar project in the past, I used the TPIC6259 latch for the 'columns', since this is an 8bit addressable latch, with power driver built in (pull down). With this, four lines selected which display was enabled. One was the 'select', and the other three the address. we turned off the select, set up the next display pattern on the register driving the rows, selected the new column, and re-enabled the select. Worked well.

Best Wishes

[NeoMatrix]

hello guest

i want to buy the kit as i am working in saudi arabia middle east can u tell me how could i buy that kit i am very much interested

thank u

[Gizz]

For anyone who wants the kit, please email

sales@tgbconsulting.co.uk

or send me a PM on CCS forum, but email will be quicker.

Regards, Gizz (aka Guest in post above!)