MPC5775K pin 8

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MPC5775K pin 8

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nikola_stevanov
Contributor I

I've been searching for an answer for 5 days now, so you guys are my last hope...

Long story short: Subaru is using Continental SRR3-A ( https://fccid.io/OAYSRR3A ) radar module in their vehicles for blind spot detection, and, after a lot of research, it turns out that the control chip in this module is NXP MPC5775K.

2419387-1.png

In the vehicle, there is a BSD/RCTA OFF switch, which is disabling blind spot monitor. The question is: when BSD/RCTA OFF switch is ON (this is pin 8), does it disable transmitter (eg. cuts power to transmit antenna), or it leaves transmitter on and just disables the alerting over CAN bus? 

Subaru support was of no help, here are the documents for reference:

Subaru Crosstrek Service Manual - Blind spot detection/rear cross traffic alert Wiring diagram - Wir... 

2017_crosstrek-wiring-system-gt-blind-spot-detectionrear-cross-traffic-alert.png

Subaru Legacy Service Manual - Electrical specification - Control module i o signal 

Terminal No.

Content

Measuring condition

Standard

Radar sensor LH (master)

Radar sensor RH (slave)

1 ←> Chassis ground

Private CAN H

Private CAN H

Always

1 M- or more

2 ←> Chassis ground

Master CAN H

Always

1 M- or more

3 ←> Chassis ground

4 ←> Chassis ground

Left mirror LED output

Right mirror LED output

 Ignition switch OFF > ON

 BSD/RCTA OFF switch OFF > ON

 When indicator is ON: 2.5 — 10.5 V

 When indicator is blinking: 0 ←> 2.5 — 10.5 V

 When indicator is OFF: Less than 1 V

5 ←> Chassis ground

Ignition power supply

Ignition power supply

Ignition switch OFF > ON

Less than 1 V > 9 — 16 V

6 ←> Chassis ground

Private CAN L

Private CAN L

Always

1 M- or more

7 ←> Chassis ground

Master CAN L

Always

1 M- or more

8 ←> Chassis ground

BSD/RCTA OFF switch

 Ignition switch ON

 BSD/RCTA OFF switch OFF > ON (while pressing and holding the switch)

Less than 1 V > 9 — 16 V

9 ←> Chassis ground

10 ←> Chassis ground

GND

GND

Always

Less than 1 -

and

MPC5775K Hardware Design Guide, Rev. 2, 6/2015

https://www.nxp.com/docs/en/application-note/AN4888.pdf (I believe the pin layout is on page 38).

From what I could conclude, shorting the pin 8 does block the transmitter, but I would really appreciate experts opinion!!!

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petervlna
NXP Employee
NXP Employee

Hi,

I am not sure what you are trying to achieve, but subaru wont tell you how their SW works. Most probably they don't even know as the module is coming from third party (standard usecase).

The question is: when BSD/RCTA OFF switch is ON (this is pin 8), does it disable transmitter (eg. cuts power to transmit antenna), or it leaves transmitter on and just disables the alerting over CAN bus?

You are talking about MPC5775K pin 8, but no further information:

pin 8 on which package. I can clearly see that it is MPC5773N which is device not offered to market and it is customer specific.

Peter

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