Schematic Review - Localization Board

Owned by Rayyan Mahmood
Last updated: Sept 19, 2024 by Hoang Dang
3 min read

Part Reviews

Reviewer Name

Manufacturer Part Number

Symbol Name

Footprint Name

Comments

Reviewer Name

Manufacturer Part Number

Symbol Name

Footprint Name

Comments

Rayyan Mahmood

NCV8114ASN180T1G

NCV8114ASN180T1G

1.8V_Output_LDO

  • Need a revision of the TVS diode and the terminal block

    • image-20240909-033255.png Essentially a power protection circuit. Saves designer from incorrect connection to connector.

      • Schottky diode blocks reverse current if battery connected opposite way

      • TVS diode prevents transient voltage spikes and clamps if voltage of 6.4V is detected

        • Switch TVS diode for a diode which clamps at about 4V

  • Check the choice of LED

    • image-20240909-034118.pngGood work showing calculations with notes

  • IC is good (both footprint and schematic symbol)

  • LEFT REMAINING COMMENTS BELOW FOR POWER.SCHDOC

Rayyan Mahmood

ICM-20948

IC_9DOF_IMU_W24

ICM20948 - 9DOFIMU

  • Check the footprint of the IMU since there is a slight different comparing to the rev 1 footprint

  • Need to add the test point/debugging feature later

  • Checking if we need to use the AUX/DA feature since the rev1 does not use it too

Rayyan Mahmood

TXB0104PWR

TXB0104PWR

TXB0104PWR 4-bit directional voltage-level translator

  • The purpose of this one is changing the 3.3V from the MCU to 1.8V to suit in the IMU

  • Need to use 2 since there are not enough pins to change from only one 4-bit? Maybe find the another one with enough pins if we can?

  • Maybe need a test point just in case there is something wrong with this one

Schematic Sheet Reviews

power.SchDoc (<Rayyan Mahmood>)

  • Add a second LED for 1.8V outimage-20240909-040123.png

    • I am concerned that the smallest voltage dropout voltage of our LED test (and the normal LED testing I searched online too) is 2V, which is bigger than the 1.8V so it would not be efficient through my research. Do you want me to still add it?

  • image-20240909-040141.png Change the colour of this title to match the colour of “GND”, “3V3”, etc.

  • Add test points for 1.8V and 3.3V and a GND test point as well. ✅

  • Look at the 48-17V buck schematic and see which TPs were used for the power and GND and use the exact same ones here ✅

  • Annotate schematic → label components ✅

    • image-20240909-041031.png Click annotate schematics quietly and that’ll do it

GPS_Module.SchDoc (<Rayyan Mahmood>)

  • image-20240909-041757.png Put GND pins at the bottom like you did with the filtering caps ✅

  • image-20240909-042024.png Is this going to be a firmware feature? As in will firmware be needed to “detect_antena”?

    • This is what I am understand from the datasheet, please correct me if I am wrong. Since we use the external antenna, we need to use the detect antenna to check if the antenna will be working or not in the long distance. And yes, this is a firmware feature.

  • We can place TPs afterwards for this as we continue to work through it as we learn more about RF and antenas as required.

    • Still may potentially add external antenna

      • I think we have to add it and would you suggest where I should add the test point?

  • Annotate schematic → label components

    • image-20240909-041031.png Click annotate schematics quietly and that’ll do it

  • image-20240909-042432.png Can you explain and justify this 1kohm resistor here? After briefly checking datasheet, I am seeing mixed opinions on it depending on if there is a “rechargable battery” being used which I don’t think is applicable to us.

    • Ok I just ask Billy about it. First of all, the rechargeable battery is separated VCC to the voltage input (look at my new schematic). He just said that it is dependent on us whether we want to buy a rechargeable or not.

Generic Schematic Reviews

Net Naming (<Reviewer Name>)

All major nets named
No duplicate net names, or nets with multiple net names
Differential pairs end with _N and _P
Active low signals are indicated with either a “_n” at the end or with overbar notation (using a “\” character after each letter in the net name, i.e. E\N\)

Wiring and Connections (<Reviewer Name>)

No 4 point connections
All unconnected pins have an ERC directive
Devices sharing an I2C or SPI bus must be simultaneously powered on/off (i.e. by powering them all off of the same power rail) - prevents unpowered devices from pulling the bus low
Lines that require pull ups are pulled up in exactly one place (not pulled up multiple times, or missing pull-ups)

Component Labels (<Reviewer Name>)

ICs show part number
Resistors show resistance value
Capacitors show capacitance and voltage rating
For capacitors, voltage rating is 2x higher than expected voltage for low-voltage nets (<12V), 1.5x higher for high-voltage nets (>12V)
Inductors show inductance and rated current
Ferrites show impedance @ frequency value
Diodes show part number, voltage rating, and current rating (if applicable). Exception is for LEDs, which only need part number

Design-for-Test (<Reviewer Name>)

All voltage rails have test points and an LED indicator
Enable/shutdown/reset/etc. lines for ICs have test points
Communication interfaces have test points (i.e. I2C, SPI, UART)
All sensor outputs have test points
Any other signals that might want to be checked during testing should have a test point