16-48 pin Multi slow PWM

[krohtech]

Hello Everyone,

Finally, after reading dozens of posts I have gotten the configuration fuses and MPASM working for my 18F migration. WOW three months ago I was using basic stamps, what a great help this forum has been.

I have seen several commercial products using a single PIC18F to do up to 48 channels of PWM for controlling RGB LEDs. I would really like to try this. I really only need 16 channels but would love to know how 48 channels is accomplished. I have looked at Darrel’s Multi SPWM and think it is really cool but do not believe you could do 48 channels at 100 cycles per second and still have the horsepower to decode DMX on a single chip. In Microchip application note AN1074 the author shows a method of using a common leading edge and common frequency software PWM with different duty cycles. The example is for three channels. I am not ready to try a assembly project like this yet as I just starting to get comfortable with PBP. I am wondering if anyone has employed a similar method in PBP, and could this be expanded to more channels.

Microchip application note AM1074:
http://www.microchip.com/stellent/id...pnote=en524189

Here is the website of the product that can do an amazing 48 channels:
http://celestialaudio.com/dmx_led/index.html

Everything I read about software PWM leads me to believe that 48 channels is quite an accomplishment.

Thank You for your time.

[Darrel Taylor]

To my knowledge, 48 simultaneous PWMs at 100hz with 8-bit resolution is not possible using a single PIC.

However, that many channels using BAM (bit angle modulation) instead of PWM is very possible. Might even have time left for the DMX reception.

Bit Angle Modulation (BAM) in a PIC
http://www.picbasic.co.uk/forum/showthread.php?t=7393
<br>

[krohtech]

Thanks Darrel

That’s very interesting, how is BAM coded in PBP?

[lanyong]

To my knowledge, 48 simultaneous PWMs at 100hz with 8-bit resolution is not possible using a single PIC.

However, that many channels using BAM (bit angle modulation) instead of PWM is very possible. Might even have time left for the DMX reception.

Bit Angle Modulation (BAM) in a PIC
http://www.picbasic.co.uk/forum/showthread.php?t=7393
<br>

see here:http://www.seachip.com.cn/product.files/SC-DMX-48D.htm

i can get the 100Hz 8 bit pwm at least.