Tony L-Iowa
TVWBB Fan
Curious if you all think this idea would be feasible as a "future upgrade".
The HM already contains an optional single TC port (port 0) with the added SMC amplifier circuitry. Would it be feasible instead of installing the thermocouple jack to instead break out the TC signals and perhaps an additional port expansion selector signal to an external add on box that contained a set of thermocouple jacks and a multiplexer chip to route the selected port signals back to the currently existing TC amp circuit? Then, use the Pi/ATMega to control the port switching and data collection process of going between multiple external TC ports? It may require something like a new HM serialized constrol/switching signal to the external demuxer/muxer to keep it down to minimal wires (e.g. power, gnd, serialized control signal, TC +/- feedback signals).
I could see the TC sensor sampling times would likely slow down based on the number of external ports expanded but can anyone else think of reasons why this may or may not be feasible without needing to change the HM circuitry and current board design? It sure seems like a potentially viable way to get expanded TC port support without spending a ton of extra money (i.e. some wires, external board with mux/demux chips and TC ports). I could see most of the work would likely be in software updates to do the switching/sampling logic and changes to control how many TC ports are external switched.
Thoughts?
The HM already contains an optional single TC port (port 0) with the added SMC amplifier circuitry. Would it be feasible instead of installing the thermocouple jack to instead break out the TC signals and perhaps an additional port expansion selector signal to an external add on box that contained a set of thermocouple jacks and a multiplexer chip to route the selected port signals back to the currently existing TC amp circuit? Then, use the Pi/ATMega to control the port switching and data collection process of going between multiple external TC ports? It may require something like a new HM serialized constrol/switching signal to the external demuxer/muxer to keep it down to minimal wires (e.g. power, gnd, serialized control signal, TC +/- feedback signals).
I could see the TC sensor sampling times would likely slow down based on the number of external ports expanded but can anyone else think of reasons why this may or may not be feasible without needing to change the HM circuitry and current board design? It sure seems like a potentially viable way to get expanded TC port support without spending a ton of extra money (i.e. some wires, external board with mux/demux chips and TC ports). I could see most of the work would likely be in software updates to do the switching/sampling logic and changes to control how many TC ports are external switched.
Thoughts?