Just a quick update:
I used the far more simplified circuit, noted here:
Make a datalogger cable | Galant VR-4 > How To and Info Archive | GalantVR-4.org Mitsubishi Galant VR4 Forum
The Laptop version is what I used, not the palm version.
Then, took the RS232 and converted to TTL using the MAX232 (refer to the datasheet, it's very easy).
Then, connected to the arduino, then used the information on MMCD's page (1920 baud, 0x21 for RPM).
RPM values were very consistent and correct.
This tells me that for DSM / Mitsubishi 4G63 / Hyundai G4CP engines, that ALDL works correctly when the circuit for the interface is done correctly.
I can now proceed and take the request / responses and try and push that into the MPGuino code.
I'm waiting on an LCD display to start putting it together, but will start hacking out the code soon.
I can't get reliable readings from speed though!
I queried speed using the value noted online in a few places, and seemingly used by Evoscan (another Mitsubishi data logging / tune up tool).
The responses for speed varied wildly, see below:
Speed: Result: Dat 0: 2FDat 1: 00|Speed: 0
Speed: Result: Dat 0: 2FDat 1: 7777|Speed: 238
Speed: Result: Dat 0: 2FDat 1: D6D6|Speed: 428
Speed: Result: Dat 0: 2FDat 1: 9F9F|Speed: 318
Speed: Result: Dat 0: 2FDat 1: 2B2B|Speed: 86
Speed: Result: Dat 0: 2FDat 1: 7C7C|Speed: 248
Speed: Result: Dat 0: 2FDat 1: DDDD|Speed: 442
Speed: Result: Dat 0: 2FDat 1: ADAD|Speed: 346
Speed: Result: Dat 0: 2FDat 1: CCCC|Speed: 408
Speed: Result: Dat 0: 2FDat 1: 3333|Speed: 102
Speed: Result: Dat 0: 2FDat 1: 1313|Speed: 38
Speed: Result: Dat 0: 2FDat 1: 3232|Speed: 100
Speed: Result: Dat 0: 2FDat 1: CECE|Speed: 412
Speed: Result: Dat 0: 2FDat 1: C8C8|Speed: 400
Speed: Result: Dat 0: 2FDat 1: E6E6|Speed: 460
Speed: Result: Dat 0: 2FDat 1: A8A8|Speed: 336
Speed: Result: Dat 0: 2FDat 1: C3C3|Speed: 390
Speed: Result: Dat 0: 2FDat 1: 2C2C|Speed: 88
Speed: Result: Dat 0: 2FDat 1: 3737|Speed: 110
Speed: Result: Dat 0: 2FDat 1: 5A5A|Speed: 180
Speed: Result: Dat 0: 2FDat 1: 2929|Speed: 82
Speed: Result: Dat 0: 2FDat 1: 2D2D|Speed: 90
Speed: Result: Dat 0: 2FDat 1: 3636|Speed: 108
Speed: Result: Dat 0: 2FDat 1: 3C3C|Speed: 120
Speed: Result: Dat 0: 2FDat 1: 6C6C|Speed: 216
Speed: Result: Dat 0: 2FDat 1: 1E1E|Speed: 60
Speed: Result: Dat 0: 2FDat 1: 7C7C|Speed: 248
Speed: Result: Dat 0: 2FDat 1: 2222|Speed: 68
Speed: Result: Dat 0: 2FDat 1: 1111|Speed: 34
Speed: Result: Dat 0: 2FDat 1: 4B4B|Speed: 150
Speed: Result: Dat 0: 2FDat 1: 8989|Speed: 274
Speed: Result: Dat 0: 2FDat 1: 8686|Speed: 268
Speed: Result: Dat 0: 2FDat 1: 44|Speed: 8
Speed: Result: Dat 0: 2FDat 1: 1B1B|Speed: 54
Speed: Result: Dat 0: 2FDat 1: 66|Speed: 12
Speed: Result: Dat 0: 2FDat 1: 2424|Speed: 72
Speed: Result: Dat 0: 2FDat 1: BABA|Speed: 372
Speed: Result: Dat 0: 2FDat 1: 33|Speed: 6
Speed: Result: Dat 0: 2FDat 1: DEDE|Speed: 444
Speed: Result: Dat 0: 2FDat 1: 8686|Speed: 268
Speed: Result: Dat 0: 2FDat 1: E0E0|Speed: 448
Speed: Result: Dat 0: 2FDat 1: 88|Speed: 16
Speed: Result: Dat 0: 2FDat 1: B1B1|Speed: 354
Speed: Result: Dat 0: 2FDat 1: 2B2B|Speed: 86
Speed: Result: Dat 0: 2FDat 1: 2828|Speed: 80
Speed: Result: Dat 0: 2FDat 1: 9090|Speed: 288
Speed: Result: Dat 0: 2FDat 1: F3F3|Speed: 486
Speed: Result: Dat 0: 2FDat 1: DD|Speed: 26
Speed: Result: Dat 0: 2FDat 1: 2B2B|Speed: 86
Speed: Result: Dat 0: 2FDat 1: EDED|Speed: 474
Speed: Result: Dat 0: 2FDat 1: 5454|Speed: 168
Speed: Result: Dat 0: 2FDat 1: C3C3|Speed: 390
Speed: Result: Dat 0: 2FDat 1: 3C3C|Speed: 120
Speed: Result: Dat 0: 2FDat 1: E0E0|Speed: 448
Speed: Result: Dat 0: 2FDat 1: 6767|Speed: 206
Speed: Result: Dat 0: 2FDat 1: 9F9F|Speed: 318
Speed: Result: Dat 0: 2FDat 1: B4B4|Speed: 360
Speed: Result: Dat 0: 2FDat 1: D6D6|Speed: 428
Speed: Result: Dat 0: 2FDat 1: 1F1F|Speed: 62
Speed: Result: Dat 0: 2FDat 1: 3D3D|Speed: 122
Speed: Result: Dat 0: 2FDat 1: F9F9|Speed: 498
Speed: Result: Dat 0: 2FDat 1: 1E1E|Speed: 60
- My little car couldn't ever achieve speeds of 498km/hr, and if it did, I certainly wasn't being an eco driver - maybe the calculation is wrong.
This gives me solid confirmation that the circuit works tho, this is great.
If it wasn't the circuit that fixed it, it would have been the 10ms delay after the data was requested.