Hi all
I have been working on a custom made 7 x 11 led matrix for some time and have just got it fully functional.
I have 77 leds each with their own 100 ohm series resistor wired up in a 7 x 11 grid.
Each of the columns has its anodes commoned up then each of the rows has its cathodes commoned up.
I am using a pic16f877 micro to drive irf9630 p mosfets for the anodes and irf630 n mosfets to drive the cathodes, forgive the use of the word drive in this sentence because it may be a bit misleading but you know what I mean.
I have also written an application in vb.net which allows me to 'draw' my picture by switching on the led's pictorially then export the code, while this may seem basic, it saves huge amounts of work for animations.
My questions going foward to version 2 is has anybody got any experience with i2c port expanders eg the microchip 16 bit MCP23016 because larger and denser led arrays will soon chew up all of my available io (my 7x11 already uses most of my available io). Would they be effective for large led arrays (of course via mosfets still)
Also when using large scan rates rather than static images on the led array can you get away with using a smalled (or none whatsoever) series resistor. (I am using a 5 volt supply for the led's also)
Any suggestions would be appreciated
Bruce
I have been working on a custom made 7 x 11 led matrix for some time and have just got it fully functional.
I have 77 leds each with their own 100 ohm series resistor wired up in a 7 x 11 grid.
Each of the columns has its anodes commoned up then each of the rows has its cathodes commoned up.
I am using a pic16f877 micro to drive irf9630 p mosfets for the anodes and irf630 n mosfets to drive the cathodes, forgive the use of the word drive in this sentence because it may be a bit misleading but you know what I mean.
I have also written an application in vb.net which allows me to 'draw' my picture by switching on the led's pictorially then export the code, while this may seem basic, it saves huge amounts of work for animations.
My questions going foward to version 2 is has anybody got any experience with i2c port expanders eg the microchip 16 bit MCP23016 because larger and denser led arrays will soon chew up all of my available io (my 7x11 already uses most of my available io). Would they be effective for large led arrays (of course via mosfets still)
Also when using large scan rates rather than static images on the led array can you get away with using a smalled (or none whatsoever) series resistor. (I am using a 5 volt supply for the led's also)
Any suggestions would be appreciated
Bruce