Commenting in vehicleProfile.json

Cali_Chuck

@aol - as I start wrapping up this latest phase of CAN/OBD/UDS signal hunting I am wanting to maintain my own private vehicleProfile.json file which I can then cut/paste discreet channels in or remove at will.

The maintenance problem is that there's no way to make sense of the cacophony of PIDs, channel IDs and formulas. What I need is to be able to comment the file without breaking RC config import.

I've tried a couple of standard Json commenting strategies, anything with "//" seem to fail. But this one appears to take... so I am in the process of building a "master" json file to test. Basically adding a "comment" field to your PID format which I assume your parser will just toss. Is this correct?

		{
			"pid": 134,
			"comment": "STEERING WHEEL SPEED (DEG/SEC) - CAN 0x086 b30 l9",
			"equation": "bitsToUintLe(raw,31,9)*5",
			"obdHeader": 0,
			"channelId": 12,
			"deviceType": 12
		},
		{
			"pid": 134,
			"comment": "STEERING WHEEL ANGLE SIGNED (DEG) - CAN 0x086 b16 l13",
			"equation": "if( bitsToUintLe(raw,29,1), bitsToUintLe(raw,16,13)*0.1, bitsToUintLe(raw,16,13)*-0.1)",
			"obdHeader": 0,
			"channelId": 1001,
			"deviceType": 12
		},
		{
			"pid": 134,
			"comment": "FRONT TIRE ANGLE SIGNED (DEG) - (SYNTHETIC STEERING WHEEL CONVERTED TO TIRE ANGLE)",
			"equation": "if( bitsToUintLe(raw,29,1), bitsToUintLe(raw,16,13)*0.1, bitsToUintLe(raw,16,13)*-0.1)*0.07666667",
			"obdHeader": 0,
			"channelId": 70546,
			"deviceType": 12
		},

A test RCZ import seems to have worked with these three fields, so I am going to batch another 20 or so signals and see if anything breaks.

What would be most cool / useful is if I could attach per-line comments on the right in the C++ "// comment..." style but AFAIK that's not compatible with Json?

Sharing here if in case this is indeed a problem I'd like to have you wave me off sooner than later, or suggest a better alternative. Fully recognize this is not a normally supported use case. Thank you.

Cali_Chuck

Update.... I've completed redoing my entire baseline config - without adding all the new signals in yet. No problem with embedding the "comment" field in each individual PID. Have 77 signals presently defined, each with a discrete comment so I can tell them apart. Tomorrow will load up 30 of the new signals.

So I will effectively be maintaining my RC vehicle config file on my desktop from here out. Really convenient for this back-engineering stuff.

aol

JSON is data only format, so there's no standardised comments like C++ etc. As we're using a standard parser libraries for all the .json file, we cannot do C++ style, or anything like that easily.

But any unknown field will be just ignored. This means parser will just ignore the field, but it will be lost when writing back to the file.

If you feel it's important, I can add the "comment" field to the parser, and then it would be persisted through writes.

edub

aol

A comment field would be nice. I'm on the cusp of sharing profiles I dynamically build and the comment field would let me propagate that without having a sidecar document with the mappings explained.

A even better solution would be an ability to just name the channels.

Cali_Chuck

Not asking for a feature add on my end - just happy it works. My use case is one-way transfers of configs from PC to IOS device. I think I've already exceeded what you're likely to support even if you made "comment" items persistent.

I've now got around 100 channels defined and it's working great. To give you some idea of the extent of my "comment abuse" here are some examples. I started with simple single comment inside a CAN PID definition like this:

{
	"pid": 256,
	"comment": "SPEED 25 - CANDIDATE - RAW UNFILTERED HIGH-HZ (KPH) / CAN 0x100 B32 L16",
	"equation": "bitsToUintLe(raw,32,16)*0.01",
	"obdHeader": 0,
	"channelId": 26214404,
	"deviceType": 12
},

But today when I turned to OBD it got tougher because I needed multiple comment lines due to how you group arbitrary numbers of PIDs inside the Slow and Fast containers. So if you went for persistence you'd need to preserve more than one comment field, and in the intended order. Like this.

"selectedChannels": [
	{
		"comment": "OBD FAST CHANNELS",
		"deviceType": 5,
		"comment": "MAP - 10027 ($0B)",
		"comment": "TIMING ADVANCE - 10028 ($0E)",
		"comment": "SHORT/LONG TERM FUEL TRIM B1+B2 - 10033 TO 10036 ($06 - $09)",
		"comment": "FUEL RAIL PRESSURE (DIESEL) - 10054",
		"comment": "COMMANDED AFE LAMBDA - 10074 ($44)",
		"comment": "ETHANOL FUEL CONTENT - 10077 ($52)",
		"comment": "CUSTOM - O2 SENSOR 1 B1, O2 SENSOR 1 B2",
		"comment": "CUSTOM - VGT CONTROL",
		"channelIds": [
			10027,
			10028,
			10033,
			10034,
			10035,
			10036,
			10054,
			10074,
			10077,
			41948041,
			1058650,
			2107226			
		],
		"priority": 2
	},

I built this trial and error in realtime, and realize its probably possible to just group all these sequential comments in a single blob. Haven't gotten that far. In addition, I've taken to creating 1, 2, or even 3 line pure comment "headers" above related sections of signals. Like this:

{
	"comment": "OBD READ DATA BY IDENTIFIER (RDIB) CUSTOM OBD CHANNEL DEFINITIONS"
},

And like this:

{
	"comment": "TEAM PLUS TIRE TEMP & PRESSURE PIDS",
	"comment": "ON SECONDARY PRIVATE CAN BUS"
},

I don't see any way you could realistically be expected to process and persist such things, esp in intended location.

That's the other thing...my master file is first level sorted by signal category, then second level sorted by ascending PID inside each category. I note that when I export configs from my phone the order is not always consistent. It seems far too much to ask to have you start managing your internal config format for a small number of us DIYers. I just am grateful for the json file.

aol

Cali_Chuck JSON is a key value system, where the key needs to be unique. So this is against the standard. I would use \n as a line delimiter inside the comment field.

Cali_Chuck

aol fair point. I'm on deadline to get this working for a trackday Friday, but will clean it up as you suggest.

Assume you mean something like this:

		"comment": "\n
			MAP - 10027 ($0B)						\n
			TIMING ADVANCE - 10028 ($0E)					\n
			SHORT/LONG TERM FUEL TRIM B1+B2 - 10033 TO 10036 ($06 - $09)	\n
			FUEL RAIL PRESSURE (DIESEL) - 10054				\n
			COMMANDED AFE LAMBDA - 10074 ($44)				\n
			ETHANOL FUEL CONTENT - 10077 ($52)				\n
			CUSTOM - O2 SENSOR 1 B1, O2 SENSOR 1 B2				\n
			CUSTOM - VGT CONTROL						\n
		",