equation

[gerhardvilsecker]

Does anyone of you guys know how to query signed values in wican eqation?
I have found following equation syntax on a VW ID.3 CAN website:
signed(B122^24+B132^16+B14*2^8+B15)/8583,07123641215 = total ack discharge
in Wican syntax this is:
([B18:B19]*65536 + B20:B21)/8583.07123641215
result is wrong due to missing "signed" function. When I try signed([B18:B19]*65636 + B20:B21)/8583.07123641215 Wican adapter resets to factory defaults during reboot :-(

PS: total ack charge is properly working. The equation here is:
([B14:B15]*65536+[B16:B17])/8583.07123641215

From my point of view this is a very interesting date. Why?: with total charge discharge along with odometer you can calculate "real" power consumption of your car...

[gerhardvilsecker]

figured it out by myself. In case it is useful for someone:
total acknowledged discharge is a signed 32bit decimal in VW ID.3=Cupra Born.
equation is: ([B19:B20]*65536 + [B21:B22] - 4294967296)/8583.07123641215
4294967296 corresponds to 2^32
All you have to do is subtract 2^32 from result of [B19:B20]*65536 + [B21:B22]. Result is a negative decimal representing total discharged in kWh.

[meatpiHQ]

You can use singed instead of [Bx:By] you can use [Sx:Sy]

[gerhardvilsecker]

sometimes life is so easy :-) Thank you very much. Just to be sure: So if I have four bytes in a row i could use?:
[Sw:Sz]
Which would be in my case: [S19:S21]

[meatpiHQ]

Yes that's right, if you want 4 bytes it should be [S19:S22]

[gerhardvilsecker]

Hi Ali, tried to change equation to your sggested one today. Unfortunately it was not working. I got no answer while using [S19:S22].
When I reverted to my "homemade" equation it worked immediately again...

[meatpiHQ]

Ok thats weird. I'm on holiday now, I'll test it when I'm back next week.

Your homemade equation looks good, I'm actually surprised that the parser is not failing :)

[gerhardvilsecker]

Another question: Is there also an equation for ascii strings available? Need to get 7 bytes from OBD return code interpreted as text.
Thanks in advance.

[gerhardvilsecker]

@meatpiHQ: Had a look into your source code. I am not a C programmer at all. But it looks like you are currtly supporting double and signeddouble as result only. For homeassistant guys I believe it would be great to have also "raw" output like for instance [R5:R18]. This would be great espacially for multiline responses. At least my car is providing up to 4 sensor values in one multiline output. So actually I would have to implement for custom_pids all using the same PID. I experienced already timing problems doing so. With raw output we could set only one custom_pid and let homeassistant create sensors from raw data. I would very appreciate you considering this for one of your next releases. Thank you

[meatpiHQ]

That's a good idea. I also plan to support a ASCII string value to get the vin number.

[gerhardvilsecker]

@meatpiHQ Great to know :-). If you dont mind I would like to let you know my ideas in terms of how to change function evaluate_expression(uint8_t *expression, uint8_t *data, double V, double *result) in expression_parser.c:
to avoid bigger changes I would just change result variable into a struct consisting of current result variable and a new string variable.
Remaining work is only adding an if clause for expression (e.g. "R" like raw) adding all bytes from R startindex to R endindex to stringvariable in return struct. Would be minimal effort. Additionally this gives you the option to add further equations like Character string or even multiple equations in one like [C5:C18,C19:C32,B33:B34]. C5:C18 = String, C19:C32 = string, B33:B34 = long (That would be the equation for my VW.ID3 GPS longitude, latitude, altitude PID :-) Have a great holiday...