Rev 3.1 PD validation

https://university-of-waterloo-solar-car-team.365.altium.com/designs/4F041A85-6320-476B-BAA5-BC219D4A1B9F?variant=[No Variations]#design

Components removed:

• R127

• R6

Components adjusted/fixed:

• R135 (resoldered)

• C61 (resoldered)

• changed R7 (4.7k → 1.21k)

At this point I flashed the controller board with the PD firmware (power_distribution) and connected the controller to PD; after soldering some jumper wires (for VBAT and GND), the board was connected to the DC power supply. The power supply was set to 13.5 V with a 0.80 A current limit; when the board was powered on I noticed that some LEDs were periodically blinking on and off (LED4 and iirc LED27 and LED23). I was also getting incorrect voltage readings for V5 (5 V) and V1 (3.3 V).

After probing and inspecting the bergstak connector, I found out that the pins of the connector were not actually soldered onto the pads (floating pins) so after removing the bergstak with the heat gun and firmly placing it down, the bergstak was resoldered. Then I probed it to make sure there were no shorts between the pins and that the bergstak was soldered properly.

I then tested the continuities between the rails (VBAT, 5V, 3V3, and GND) using the test points to make sure I didn’t bridge any pins on the bergstak:

• VBAT and 5V

• VBAT and 3V3

• VBAT and GND

• 5V and 3V3

• 5V and GND

• 3V3 and GND

After confirming that there were no shorts between VBAT, 5V, 3V3, and GND, I connected PD to the power supply again (13.5 V, 0.8 A limit) and powered on PD and flashed the controller board with the power_distribution firmware under the pd_smoketest branch.

This program turns on all load switches so I was able to measure the following:

As shown in the table, Main_Pi and Spare_5V_2 is not giving an output voltage (we are expecting both to give ~5V).

Ryan said that there’s no firmware reason for both Main_Pi and Spare_5V_2 to both be zero and he suggested to take a look at the I/O expander connected to both Main_Pi and Spare_5V_2 (which is U10 in this case). More specifically, the following pins: 13, 14, 15, 16, 17, 18. After confirming that these pins are not shorted with one another, I powered on PD and measured the following:

From the table, you can see that the load switches (U13 and U14) are receiving the EN signals (MAIN_PI_B+ EN and 5V_SPARE_2_EN) so there must be something wrong at U13 and U14 rather than U10.

I first checked for shorts for the output pins of U13; in this case I checked pins 12, 13, 14 with GND, VBAT, 5V, and 3V3. I also did the same for the output pins of U14 (8, 9, 10). In both scenarios, there were no shorts. So then I then checked the surrounding components.

I did the following:

• I checked the orientation of both LED14 and LED17 using the diode mode from a DMM, to make sure they weren’t soldered the wrong way (in this case they were both soldered correctly)

• I checked for shorts with the other passive components (I found out that they were soldered correctly)

• I added more solder to certain components that I thought were lacking enough to create a solid connection between the component and the pad

At this point, both LED14 and LED17 still did not turn on so I decided to measure the voltages of the input pins of U13 and U4.

So there must have been an issue with the components surrounding

EDIT THIS:

• i found out that led14 turns on when i pushed down on pin2 of U13 (fixed this by soldering)

• i find out that led17 turns on by probing pin 4 of R89 (most likely soldering issue)

• i find out that led22 turns on by probing pin 4 of R115 (most likely soldering issue)

(IGNORE FOR NOW):

• power_distribution

  • automatically detects as rear board (in minicom)

    • LED27, LED23, LED4 stay on

    • LED1 of controller board stays on

  • VBAT: ~13.5 V

  • V5: ~5 V

  • V1: ~3.3 V

  • 

• smoke_bts7200

  • LED27, LED23, LED4 stay on

  • LED1 of controller board stays on

  • 

• smoke_bts7040:

  • LED27, LED23, LED4 stay on

  • LED1 of controller board stays on

  • 

To be edited:

Potential component/soldering issues

VBAT:

• bergstak pins

V1 (3V3):

• R89 (added more solder)

• R80 (added more solder)

• bergstak pins

• R102 (added more solder)

• R132 (added more solder)

• R115 (added more solder)

V5:

• probing of I2C

  • SCL

  • SCA