openinverter forum

Posted: **Wed Jan 27, 2021 6:46 am**

Hello, fellow ev-diyers.
Could somebody please help me understand the SDU wiring from https://github.com/damienmaguire/Tesla- ... ctions.pdf

I wired the accel pedal BMW E46 (only one pot out of two) to pins 4-6-8. The setting's are on pot. It's running - though with a short dead zone, even though mins and max are set correctly.
Pot2 is set to 4095, as there's nothing connected to it.

Questions:
1. Trying to understand how does brake transducer on pins 7-10-18 differ from brake light switch on pin 15?
2. When would you use one and the other? Is this when pot2 comes into picture?
3. How does one setup one foot driving? Would it be my second out of the two pots on the e46 connected to pot2? As-is, I have no regen.

Thanks in advance .

Posted: **Wed Jan 27, 2021 6:53 am**

https://openinverter.org/wiki/Main_Board_Version_3

Posted: **Fri Jan 29, 2021 8:03 am**

Bratitude wrote: ↑Wed Jan 27, 2021 6:53 am https://openinverter.org/wiki/Main_Board_Version_3

Thanks.

So if I understood correctly, brake light switch is the input from the brake pedal - likely a vacuum switch.
While brake transducer on pins 7-10-18 is the regen input (pot2 config). Can I just connect the second pot on my BMW E46 pedal? Does it need to be inverted from the one acting as accel?

Posted: **Fri Jan 29, 2021 12:56 pm**

alexbeatle wrote: ↑Fri Jan 29, 2021 8:03 am
So if I understood correctly, brake light switch is the input from the brake pedal - likely a vacuum switch.

Brake lights are typically NOT a vacuum switch. Typically its a physical switch that the pedal activates.

Posted: **Fri Jan 29, 2021 1:48 pm**

Or on old VWs, it's a pressure switch on the master cylinder.

Posted: **Sat Jan 30, 2021 8:07 am**

DaveH wrote: ↑Fri Jan 29, 2021 1:48 pm Or on old VWs, it's a pressure switch on the master cylinder.

I believe that's the case on my VW T2 bus. In fact there're 2x of them in series for redundancy. Ok so I'll use that on the "Brake Light Switch" - pin15.

Still not sure how does brake transducer on pins 7-10-18 come into picture. Looking at LDU schematics, it's says it's optional there. Anybody?

Posted: **Sat Jan 30, 2021 4:38 pm**

alexbeatle wrote: ↑Sat Jan 30, 2021 8:07 am
DaveH wrote: ↑Fri Jan 29, 2021 1:48 pm Or on old VWs, it's a pressure switch on the master cylinder.
I believe that's the case on my VW T2 bus. In fact there're 2x of them in series for redundancy. Ok so I'll use that on the "Brake Light Switch" - pin15.

Still not sure how does brake transducer on pins 7-10-18 come into picture. Looking at LDU schematics, it's says it's optional there. Anybody?

I suggest you read. The first thing on the wiki front page is:

“Before you begin:
Please take the time to read.”

Your answer lies in the documentation of the board. It’s is very clear.

Posted: **Thu Feb 11, 2021 5:17 am**

alexbeatle wrote: ↑Sat Jan 30, 2021 8:07 am
DaveH wrote: ↑Fri Jan 29, 2021 1:48 pm Or on old VWs, it's a pressure switch on the master cylinder.
I believe that's the case on my VW T2 bus. In fact there're 2x of them in series for redundancy. Ok so I'll use that on the "Brake Light Switch" - pin15.

Still not sure how does brake transducer on pins 7-10-18 come into picture. Looking at LDU schematics, it's says it's optional there. Anybody?

I hate when people say "read". Yes, reading is good, but sometimes you've been staring at the problem for so long that nothing makes sense anymore and need another head to help alleviate some of the uncertainty. I had the same questions when I was first starting and had to go investigate.

Take a look at the attachments. The 3 pin brake input (Pins 7,10,18) is a 0-5V signal (similar to the throttle input). Likely this is a pressure sensor, hall-effect, or other type of proportional signal. Firmware uses this to calculate amount of regen. You will see this when you log onto the inverter and view the parameters under "REGEN" category. I grab this signal off of the Tesla iBooster position sensor.

If the signal is not available, then the logic uses the brake light switch as a boolean to know when the brakes are being applied and then uses a max value to regen, again in the parameters under "REGEN" category. The voltage divider uses 4.7k and 1.5k resistors which would cut a 12V input down to 2.9V (logic high). This was likely included for people doing conversions on cars that didn't have fancy brake sensors but still wanted to take advantage of regen.

Link to Firmware function

Screenshots from SDU Schematic V4

Regen Params:

Code: Select all

#define REGEN_PARAMETERS \
    PARAM_ENTRY(CAT_REGEN,   brknompedal, "%",       -100,   0,      -50,    38  ) \
    PARAM_ENTRY(CAT_REGEN,   regenramp,   "%/10ms",  0.1,    100,    100,    68  ) \
    PARAM_ENTRY(CAT_REGEN,   brknom,      "%",       0,      100,    30,     19  ) \
    PARAM_ENTRY(CAT_REGEN,   brkmax,      "%",       -100,   0,      -30,    49  ) \
    PARAM_ENTRY(CAT_REGEN,   brkcruise,   "%",       -100,   0,      -30,    124 ) \
    PARAM_ENTRY(CAT_REGEN,   brkrampstr,  "Hz",      0,      400,    10,     39  ) \
    PARAM_ENTRY(CAT_REGEN,   brkout,      "%",       -100,   -1,     -50,    67  )

Posted: **Sun Feb 21, 2021 2:43 am**

amzoo wrote: ↑Thu Feb 11, 2021 5:17 am
alexbeatle wrote: ↑Sat Jan 30, 2021 8:07 am
DaveH wrote: ↑Fri Jan 29, 2021 1:48 pm Or on old VWs, it's a pressure switch on the master cylinder.
I believe that's the case on my VW T2 bus. In fact there're 2x of them in series for redundancy. Ok so I'll use that on the "Brake Light Switch" - pin15.

Still not sure how does brake transducer on pins 7-10-18 come into picture. Looking at LDU schematics, it's says it's optional there. Anybody?
I hate when people say "read". Yes, reading is good, but sometimes you've been staring at the problem for so long that nothing makes sense anymore and need another head to help alleviate some of the uncertainty. I had the same questions when I was first starting and had to go investigate.

Take a look at the attachments. The 3 pin brake input (Pins 7,10,18) is a 0-5V signal (similar to the throttle input). Likely this is a pressure sensor, hall-effect, or other type of proportional signal. Firmware uses this to calculate amount of regen. You will see this when you log onto the inverter and view the parameters under "REGEN" category. I grab this signal off of the Tesla iBooster position sensor.

If the signal is not available, then the logic uses the brake light switch as a boolean to know when the brakes are being applied and then uses a max value to regen, again in the parameters under "REGEN" category. The voltage divider uses 4.7k and 1.5k resistors which would cut a 12V input down to 2.9V (logic high). This was likely included for people doing conversions on cars that didn't have fancy brake sensors but still wanted to take advantage of regen.

Link to Firmware function

Screenshots from SDU Schematic V4

Regen Params:
Code: Select all
#define REGEN_PARAMETERS \
    PARAM_ENTRY(CAT_REGEN,   brknompedal, "%",       -100,   0,      -50,    38  ) \
    PARAM_ENTRY(CAT_REGEN,   regenramp,   "%/10ms",  0.1,    100,    100,    68  ) \
    PARAM_ENTRY(CAT_REGEN,   brknom,      "%",       0,      100,    30,     19  ) \
    PARAM_ENTRY(CAT_REGEN,   brkmax,      "%",       -100,   0,      -30,    49  ) \
    PARAM_ENTRY(CAT_REGEN,   brkcruise,   "%",       -100,   0,      -30,    124 ) \
    PARAM_ENTRY(CAT_REGEN,   brkrampstr,  "Hz",      0,      400,    10,     39  ) \
    PARAM_ENTRY(CAT_REGEN,   brkout,      "%",       -100,   -1,     -50,    67  )

Thank you. Now I understand!

Posted: **Fri Jan 27, 2023 1:37 pm**

amzoo wrote: ↑Thu Feb 11, 2021 5:17 am I hate when people say "read". Yes, reading is good, but sometimes you've been staring at the problem for so long that nothing makes sense anymore and need another head to help alleviate some of the uncertainty. I had the same questions when I was first starting and had to go investigate.

Take a look at the attachments. The 3 pin brake input (Pins 7,10,18) is a 0-5V signal (similar to the throttle input). Likely this is a pressure sensor, hall-effect, or other type of proportional signal. Firmware uses this to calculate amount of regen. You will see this when you log onto the inverter and view the parameters under "REGEN" category. I grab this signal off of the Tesla iBooster position sensor.

If the signal is not available, then the logic uses the brake light switch as a boolean to know when the brakes are being applied and then uses a max value to regen, again in the parameters under "REGEN" category. The voltage divider uses 4.7k and 1.5k resistors which would cut a 12V input down to 2.9V (logic high). This was likely included for people doing conversions on cars that didn't have fancy brake sensors but still wanted to take advantage of regen.

Link to Firmware function

Screenshots from SDU Schematic V4

Regen Params:
Code: Select all
#define REGEN_PARAMETERS \
    PARAM_ENTRY(CAT_REGEN,   brknompedal, "%",       -100,   0,      -50,    38  ) \
    PARAM_ENTRY(CAT_REGEN,   regenramp,   "%/10ms",  0.1,    100,    100,    68  ) \
    PARAM_ENTRY(CAT_REGEN,   brknom,      "%",       0,      100,    30,     19  ) \
    PARAM_ENTRY(CAT_REGEN,   brkmax,      "%",       -100,   0,      -30,    49  ) \
    PARAM_ENTRY(CAT_REGEN,   brkcruise,   "%",       -100,   0,      -30,    124 ) \
    PARAM_ENTRY(CAT_REGEN,   brkrampstr,  "Hz",      0,      400,    10,     39  ) \
    PARAM_ENTRY(CAT_REGEN,   brkout,      "%",       -100,   -1,     -50,    67  )

Hi there, I know this is an old thread but thanks a lot for the explanation - helped me a lot as well. I also have a Tesla iBooster and it has the 4 pedal position sensors which you wire to the ECO so would you mind sharing how you tapped into which signal to wire up pins 7,10,18 on the OI board? Would really be appreciated!

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