Medallion MDC data messages

[proey]

@uuuubbbb thanks for posting.  Your post is pretty conclusive that I have two primary speedos.  I'm not sure that really changes my plan to make an MDC replacement with an Arduino mega (4 serial ports, GPS, MEFI ECM, Gauges, PC debug/logging).

Next I need to make up a wiring harness to get my gauges all working together (right now I'm doing one at a time) on the workbench and I send some 4 data byte packets to 0xC7 and see what happens if anything.

[ShuManChu]

On 10/14/2022 at 7:03 PM, proey said:

@uuuubbbb thanks for posting.  Your post is pretty conclusive that I have two primary speedos.  I'm not sure that really changes my plan to make an MDC replacement with an Arduino mega (4 serial ports, GPS, MEFI ECM, Gauges, PC debug/logging).

Next I need to make up a wiring harness to get my gauges all working together (right now I'm doing one at a time) on the workbench and I send some 4 data byte packets to 0xC7 and see what happens if anything.

Can't you use the existing wiring harness? 

[Wakeswitches]

A little off topic, but wondering if you guys know anything about the can protocol used from the 2011-15 touchscreen to the viper module. Could an arduino etc be used to read its data?
 

Cheers!

[ShuManChu]

56 minutes ago, Wakeswitches said:

A little off topic, but wondering if you guys know anything about the can protocol used from the 2011-15 touchscreen to the viper module. Could an arduino etc be used to read its data?
 

Cheers!

If you just want to read the CAN data from a working system, it would be much easier to use an off the shelf USB CAN logger + capture software, like this one: https://www.csselectronics.com/pages/can-bus-interface-savvycan

If you want to have your own microcontroller read, interpret, and then act on the CAN data, then yes I think an arduino would be able to handle that. 

[skisky89]

@Wakeswitches There's a CAN shield for most development boards, https://esphome.io/components/canbus.html

I'm leaning into using an ESP32, ZC-00020 display, logic shifter etc.

At first I was convinced all the data for my 2004 was serial, but it sounds like info intended for the tiny segmented LCD on the RPM gauge might be coming from CAN?? Wouldn't this mean I would have an extra wire or interface?

[ShuManChu]

On 2/19/2023 at 8:12 AM, skisky89 said:

@Wakeswitches At first I was convinced all the data for my 2004 was serial, but it sounds like info intended for the tiny segmented LCD on the RPM gauge might be coming from CAN?? Wouldn't this mean I would have an extra wire or interface?

2004 was the first year of the LCD screen. It does not work off of CAN, at least to my knowledge. It is integrated into the Medallion Gauge PCB, and thus only has the standard 5 wires that go to all the gauges (Power, Ground, Data, Backlight, and unused). No CAN high/low data wires are going into the gauge, so I think it is reasonable to assume that it is operating the LCD using the proprietary "A/B Bus" serial data that has been discussed in this thread. 

 

The gauge manual mentions that the MMDC uses CAN to communicate with the "Message center and modules" but I don't think that refers to the integrated LCD in the gauge.