Megasquirt CAN

Revision as of 03:23, 16 July 2015 by Brentp (talk | contribs)

Megasquirt Dashboard CAN broadcast

This CAN script enables integration with the simplified dashboard mode CAN stream. Refer to the Megasquirt documentation for enabling Dashboard mode CAN broadcast.

Channels enabled:

  • Engine RPM (RPM)
  • Throttle Position (TPS)
  • Coolant Temperature (Coolant)
  • Manifold Absolute Pressure (MAP)
  • Air/Fuel Ratio (AFR)

Additional channels can be enabled by expanding the script.

CAN Database

CAN Bus database for Megasquirt

Megasquirt Wiring

MS3-Pro MS3-Pro wiring

CAN bus connections available on MS3-Pro white connector:

  • CAN High: Pin 33
  • CAN Low : Pin 34

Photos

Megasquirt CAN RCP.jpg

--This example configured for Megasquirt Dashboard Mode

--how frequently we poll for CAN messages
tickRate = 30
--the CAN baud rate
CAN_baud = 500000
--CAN channel to listen on. 0=first CAN channel, 1=second
CAN_chan = 0
--1 for Big Endian (MSB) mode; 0 for Little Endian mode (LSB)
be_mode = 1

--add your virtual channels here
--addChannel(<name>, <sample rate>, [logging precision], [min], [max], [units label])
rpmId = addChannel("RPM", 10, 0, 0, 10000)
tpsId = addChannel("TPS", 10, 0, 0, 100, "%")
mapId = addChannel("MAP", 10, 0, 0, 250, "kPa")
cltId = addChannel("Coolant", 1, 0, 0, 200, "F")
afrId = addChannel("AFR", 10, 1, 0, 20)

--customize here for CAN channel mapping
--format is: [CAN Id] = function(data) map_chan(<channel id>, data, <CAN offset>, <CAN length>, <multiplier>, <adder>)
CAN_map = {
[1512] = function(data) map_chan(mapId, data, 0, 2, 0.1, 0) map_chan(rpmId, data, 2, 2, 1, 0) map_chan(cltId, data, 4, 2, 0.1, 0) map_chan(tpsId, data, 6, 2, 0.1, 0) end,
[1514] = function(data) map_chan(afrId, data, 1, 1, 0.1, 0) end
}

function onTick()
    processCAN(CAN_chan)
end

--===========do not edit below===========
function processCAN(chan)
    repeat
        local id, e, data = rxCAN(chan)
        if id ~= nil then
            local map = CAN_map[id]
            if map ~= nil then
                map(data)         
            end
        end
    until id == nil
end

--Map CAN channel, little endian format
function map_chan_le(cid, data, offset, len, mult, add)
    offset = offset + 1
    local value = 0
    local shift = 1
    while len > 0 do
        value = value + (data[offset] * shift)
        shift = shift * 256
        offset = offset + 1
        len = len - 1
    end
    setChannel(cid, (value * mult) + add)
end

--Map CAN channel, big endian format
function map_chan_be(cid, data, offset, len, mult, add)
    offset = offset + 1
    local value = 0
    while len > 0 do
        value = (value * 256) + data[offset]
        offset = offset + 1
        len = len - 1
    end
    setChannel(cid, (value * mult) + add)
end

map_chan = (be_mode == 1) and map_chan_be or map_chan_le
initCAN(CAN_chan, CAN_baud)
setTickRate(tickRate)

References