Guru
Joined: 08/02/2015
Location: New ZealandPosts: 1255
| Posted: 04:09am 07 Sep 2021 |
Sticking with the PICO 2040 module, good excuse to update my very rusty C coding to use the second CPU if I want to use threading.
Have made a few alterations to the final schematic, added more high power mosfet output switches for Horns, Strobes, Sirens and Lamps; these are coupled directly to the CPU with tiny mosfet drivers.
All analog inputs are multiplexed by an analog mux chip, 74HC4051 with a common Low Pass active filter.
Digital IO from the various types of zone sensors, 16 in all are connected via 74HC251D digital multiplexers. The IO stuff takes up a lot of space so have placed that on a separate plugin pcb and sits over the main pcb.
The slower LED status display leds and output relays are accessed by power serial to parallel output chips NPIC6C596A, these can drive 100ma on each IO pin; the leds will be on a small pcb connected by ribbon cable so can bolt to the front panel of the case. Haven't started this board yet, next on the list.
Main PCB 245 x 128mm:
IO Zone Inputs 100 x 60mm:
Cheers
Mike