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General notes:
used a Rev 3.0 PD assembled as rear
used one 12V nocuta fanused an electronic load fans
one NF-F12
three NF-A9’s
used an electronic load as a substitute for horn (set to 3 ohms)
anytime I refer to power_distribution firmware, it is under the pd_smoketest branch
two separate power supplies, one for PD and one for UV cutoff, both supplied with 13.5V
U2 IS NOT POPULATED FROM HERE ON OUT
Testing Fan and Horn
First I tested the horn with a power supply; I simply soldered two wires to both terminals (I’m pretty sure the horn is not polarized) and I set a power supply for 12V with a 5.0A limit.
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Pin | Reading (volts) |
|---|---|
1: OUT(put) | 0.0558 |
2: SPARE 2 3 IS | 0.0001 |
3: STR_PDL_IS | 0.0032 |
4: SPEAKER/SOLAR_SENS_IS | 0.0014 |
5: L R DVR DISP IS | 0.0031 |
6: MCI_IS | 0.0023 |
7: 5V SPARE IS | 0.0005 |
8: MAIN_REAR_PI_IS | 0.0015 |
9: DVR_REAR_DISP | 0.0032 |
10: PA6 MUX SEL1 | 3.3055 (periodically changes) |
11: PA5 MUX SEL2 | 3.3057 (periodically changes) |
12: GND | 0.0002 |
13: PA3_MUX_SEL4 | 3.3052 (periodically changes) |
14: PA4 MUX SEL3 | 3.3054 (periodically changes) |
15: Ē | 0.0014 |
16: UV_VBAT_IS | 0.0129 |
17: FAN IS | 0.0031 |
18: MAIN_DISP/BMS_IS | 0.0013 |
19: LEFT/REAR_RIGHT_CAM_IS | 0.0014 |
20: SPARE 1 IS | 0.0012 |
21: (closed) | 0.0028 |
22: FRONT/REAR_TURN_LIGHT_IS | 0.0021 |
23: DAYTIME/REAR_BRK_IS | 0.0003 |
24: 3V3 | 3.3055 |
TO BE EDITED:
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IS pin was: 0.0033V
other IS pins from other load switches were: 0.2501V (U5), 0.1498V (U1)
DEN pin was: 0.0404V
other DEN pins from other load switches were: ~2.67V
Problem:
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R24 wasn’t soldered down properly (connected to IS pin)
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Now you can see that the voltage at pin 16 is something much more reasonable now that I have replaced U11. However, there is still an issue where the current readings in minicom as shown here:
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When I have one fan and the horn connected to UV cutoff, the current draw is ranges from 32 - 39mA which doesn’t make sense because the power supply connected to UV cutoff displays a current of about 4.29A. I decided to check the voltage of the IS pins (pin 4) of the following load switches:
Component | Reading (volts) |
|---|---|
U4 | 0.0033 |
U5 | 0.2501 |
U1 | 0.1498 |
As you can see from the table, 0.0033V is quite a bit lower than 0.1498V and 0.2501V. Referring back to the datasheet of U4:
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This basically means that if the DEN pin is low (low voltage), then IS becomes high impedance (which explains the low voltage 0.0033V).
So then I decided to check the voltage of the DEN pins (pin 3) of the load switches:
Component | Reading (volts) |
|---|---|
U4 | 0.0404 |
U5 | 2.7325 |
U1 | 2.7244 |
As you can see from the table, 0.0404V is significantly lower than 2.7V so I knew that the DEN pin of U4 was set to low, but it needs to be set to high so that the IS pin does not become a high impedance.
Through inspection, I found that R24 and R22 weren’t soldered properly.
R24 connects to the IS pin (after resoldering it closes the connection between the IS pin and R25 [to 6-pin PD connector])
R22 connects to the DEN pin (after resoldering it closes the connection between the DEN pin and FUSED_VBAT+)
After resoldering both resistors, the voltages for the IS and DEN pins of U4 are:
Pin | Reading (volts) |
|---|---|
IS | 0.2621 |
DEN | 2.6721 |
So now the voltages are more in line with the other load switches.
Current Readings in minicom
This section contains screenshots of the UV VBAT current readings in minicom for different scenarios. In the publish_data.c file located in /firmware_xiv/projects/power_distribition/src/, I’ve commented out this line here so I could focus on current readings:
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As of July 26, 2021, the current is scaled for a BTS7040 rather than a BTS7004 which is the MPN of U4. The current readings are off (minicom doesn’t match what the power supply draws).
Test case | Power supply current draw (amps) | minicom current readings |
|---|---|---|
4 fans running + horn | 4.81 |  |
3 fans running + horn (three NF-A9’s) | 4.45 |  |
2 fans running + horn (two NF-A9’s), | 4.36 |  |
1 fan running + horn (one NF-A9) | 4.29 |  |
horn by itself | 4.19 |  |
4 fans running w/o horn | 0.69 |  |
3 fans running w/o horn (three NF-A9’s) | 0.28 |  |
2 fans running w/o horn (two NF-A9’s) | 0.19 |  |
1 fan running w/o horn (one NF-A9) | 0.09 |  |
0 fans and no horn | 0.02 |  |