The best way to control an 8 x 8 LED matrix
DeeLuxx
Posts: 14
Hi there,
I recently got a couple of 8 x 8 LED matrices of futurlec.com to play around with.
i controlling them with my BS2 and using 2 74LS164 8 bit shift registers to control them.
One register takes care of refreshing the display line by line and the other displays the line data. the register that does the line refreshing is connected to the negative side of the display so i have to use 8 general purpose NPN transistors to let it switch different rows on and off.
it works but rather crudely as the registers dont like to output stuff while data is being shifted into them and also the fact the the 74LS164 registers are like the oldest ones around.
i was considering using a SX20AC to take care of the line data and a fast(er) shift register to take care of refreshing the display.
the idea is to use multiple matrices to make a bigger display so i would use one shift register to take care of refreshing every display then one chip of some sort to do the line data of each individual display. each chip would be controlled by a propellor and communication would be through SPI.
Im really new to this so any suggestions would be helpfull.
I was also trying to find a way to vary the brightness of each dot on the display and i looked into 8 channel DACs but there a bit expensive.
are there any other ways to do this?
I recently got a couple of 8 x 8 LED matrices of futurlec.com to play around with.
i controlling them with my BS2 and using 2 74LS164 8 bit shift registers to control them.
One register takes care of refreshing the display line by line and the other displays the line data. the register that does the line refreshing is connected to the negative side of the display so i have to use 8 general purpose NPN transistors to let it switch different rows on and off.
it works but rather crudely as the registers dont like to output stuff while data is being shifted into them and also the fact the the 74LS164 registers are like the oldest ones around.
i was considering using a SX20AC to take care of the line data and a fast(er) shift register to take care of refreshing the display.
the idea is to use multiple matrices to make a bigger display so i would use one shift register to take care of refreshing every display then one chip of some sort to do the line data of each individual display. each chip would be controlled by a propellor and communication would be through SPI.
Im really new to this so any suggestions would be helpfull.
I was also trying to find a way to vary the brightness of each dot on the display and i looked into 8 channel DACs but there a bit expensive.
are there any other ways to do this?
Comments
MAXIM SSemiconductor makes a great matrix LED driver, but sadly I don't remember the number of it. I'm sure one of the other folks will chime in with the appropriate number. Meanwhile, here are some 8 x 8 LED matrix LED drivers that are newer than the one which is usually used. It will give you the idea of how they accomplish it:
http://www.maxim-ic.com/quick_view2.cfm/qv_pk/4910
Regards,
Bruce Bates
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
When all else fails, try inserting a new battery.
Here is the Maxim 8x8 matrix LED driver which eluded me earlier:
http://www.maxim-ic.com/quick_view2.cfm/qv_pk/1339/t/al
That is the unit most often used with the PBAIC Stamp. Sorry for not remembering the number.
Regards,
Bruce Bates
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
When all else fails, try inserting a new battery.
I was looking at that driver on various websites and its about $9-10 which is a bit much (i want to use 16 matrices so thats almost $160 just for the drivers)
Is there a cheaper alternative to these drivers?
I would stilllike to have the variable brightness feature.
thanks