I've made a few Custom Led Matrix that Im planing on using max7219 chips to control them, and I'm wondering if anyone can help me with the connections from matrix to the max7219?
I've found several on 8x8 matrix, but nothing to help with odd configurations.
I have (2) 5x9 Matrix that I'd like to have together
and one 4x27 that would be on its own.
all running the same 3mm LEDS, all cathodes in columns and anodes together in rows.
Also would I be able to place ONE resistor on the max7219 (again all LEDs have same requirements) or would I need to have one for each row/column?
With Max7219 you only need 1 resistor per chip to set the current for all the LEDs. Plus 2 caps.
For 2 5x9 you will need 3 max7219. And you will have to cut your matrix into 2 5x8 plus 2 5x1. It is possible to reduce this to 2 max7219, but it will be difficult to write the code for it.
For 4x27 you will need 2 max7219. Again, you will need to cut your matrix into 3 4x8 plus 1 4x3, then join together into 1 8x8 plus one 8x8 but with diodes missing.
Thank you,
What I'm questioning however is the actual wiring between the matrix and the the max7219 chip.
what Im seeing from all the 8x8 matrixes is:
all columns wired to pins 0-7
all rows wired to pins 14-22
and 24 for the out (I assume the connect to second max7219)
Would I then be (in the case of the 4x27) using pins 14-17 for the rows on chip 1, and then 0-7 on chip one and the other 2 chips for the rows leaving 14-22 empty on all the other chips?
Is this correct? or am I way off track?
BubbleHockey:
Would I then be (in the case of the 4x27) using pins 14-17 for the rows on chip 1, and then 0-7 on chip one and the other 2 chips for the rows leaving 14-22 empty on all the other chips?
No, they don't work like that. You have to use the row and column pins on each chip to drive an isolated section of the matrix of up to 8x8. This is why I said you will have to cut your matrix to use these chips. It can be 4x27 physically, but you must cut it up in such a way that each isolated section is 8x8 or less.
Yes, with max7219 you would daisy-chain data out from the first chip to data in on the second chip and so on. The clock and latch lines to in parallel to each chip.
With ht16k33, the SDA and SCL lines go in parallel to each chip. You give each chip a different address on the i2c bus by connecting certain pins on the chip to +V or GND.
I'm not married to the max 7219, but in prep for building I did order a hand full of them, so I might as well use them. to be honest I was not aware of the HT16K33 chip, and might have been something look into.
I'll be giving the build a go this weekend, thanks for your help!