AIM CAN

MyChron 3

This section documents how to control an AIM Mychron3 Dash display, using an RCP unit via LUA scripting. The following information is a sum up of reverse engineering findings by Jean-Sebastien Stoezel documented here. Examples of LUA implementation of the the different packets documented on the Mychron 3 Hack page are provided below.

CAN Bus Initialization

The AIM Mychron3 requires a CAN bus rate of 1Mb/s, in standard form (11 bit identifiers). The following code example initializes the CAN bus channel at 1Mb/s.

 initCAN(2, 1000000)

Packet 401h: RPM, Speed, Gear blink control, Gear

 function onTick()
   local rpm = getTimerRpm(0)
   local speedmph = getGpsSpeed()
   -- Assume the gear is calculated and stored in a virtual channel.
   -- Refer to LUA scripting example to calculate the gear based on speed and RPM
   local gear = getChannel(gearId)
   local msg = {rpm % 256, rpm / 256, (speedmph % 16) % 256, (speedmph / 16) / 256, 0, 0, gear, 0}
   txCAN(0, 1025, 0, msg)
 end

Packet 402h: Temperature/Pressure fields (bottom left of display)

 function onTick()
   -- Assume different temperature values are connected to different sensors
   local temp1 = getAnalog(0)
   local temp2 = getAnalog(1)
   local temp3 = getAnalog(2)
   local temp4 = getAnalog(3)
   local msg = {temp1 % 256, temp1 / 256, temp2 % 256, temp2 / 256, temp3 % 256, temp3 / 256, temp4 % 4, temp4 / 256}
   txCAN(0, 1026, 0, msg)
end

Packet 405h: Shift LEDs, Alarm LEDs

 function onTick()
   local shiftLeds = 0
   local rpm = getTimerRpm(0)
   if rpm > 5000 then shiftLeds = shiftLeds + 1 end 
   if rpm > 6000 then shiftLeds = shiftLeds + 2 end 
   if rpm > 7000 then shiftLeds = shiftLeds + 4 end
   if rpm > 7500 then shiftLeds = shiftLeds + 8 end
   if rpm > 7700 then shiftLeds = shiftLeds + 16 end
   local msg = {0, 0, 0, 0, 0, 0, shiftLeds, 0}
   txCAN(0, 1029, 0, msg)
 end

Packet 406h: RPM range for the digital RPM readout

 function onTick()
   -- Set the RPM range
   -- Value  	 RPM Range
   -- 0	 25,000 - 0
   -- 1	 22,000 - 0
   -- 2	 20,000 - 0
   -- 3	 16,000 - 0
   -- 4	 12,000 - 0
   -- 5	 10,000 - 0
   -- 6	 8,000 - 0
   -- 7	 6,000 - 0
   -- 8	 4,000 - 0
   local rpmRange = 6 -- Up to 8000 RPM
   local msg = {0, rpmRange * 16, 0, 0, 0, 0, 0, 0}
   txCAN(0, 1030, 0, msg)
 end