Pico, Batt, and Solar Board - alanbjohnston/CubeSatSim GitHub Wiki

Building the CubeSatSim Pico

These are the instructions for building the Pico Board, Batt Board, and Solar Board.

Here is the software for the CubeSatSim Pico: https://github.com/alanbjohnston/CubeSatSim/tree/pico/cubesatsim

Pico Board v0.4

These are the instructions for building the Pico v0.4 board.

You will need these tools:

  • Safety glasses (to protect eyes while soldering or trimming leads)
  • Soldering iron with fine tip and very thin solder (I use lead-free solder, but leaded solder is easier to work with)
  • Flux pen
  • Tweezers
  • Needle nose pliers (to bend leads and hold parts)
  • Side cutters (to trim leads)

Other tools that are helpful:

  • Blue mounting putty (to hold components in place while soldering)

Assembly

Here is the Pico v0.4 PCB:

Here is the schematic:

https://github.com/alanbjohnston/CubeSatSim/blob/pico/hardware/pico/v0.4/cubesatsim-pico-0.4_schematic.pdf

Before soldering the through-hole parts, the SMD parts such as the SAW filter, SR_FRS transmitter, USB-C, and clockgen components need to be mounted.

The instructions for this are here: Pico v0.2 SMD Instructions

The v0.4 board with all the SMD parts installed looks like this:

PCB_SMD_v0 4

Through Hole Parts

First, solder the three integrated circuits (IC) U2, U4, and U8:

IMG_5351

You will need to bend the pins slightly to insert them in the PCB. Pay attention to the "dot" on the IC that marks pin 1, and make sure it is in the upper left when the board is in this position.

IMG_5352

Solder only one pin on each IC, then double check the pin 1 mark and the IC is inserted correctly before soldering the rest of the pins.

IMG_5353

Next, mount the 1x20 female sockets for the Pico U1. NOTE: You can also solder the Pico directly onto the board if you are comfortable drag soldering SMD parts.

IMG_5365

You can use the male pin headers to space and align the sockets for the Pico.

IMG_5366

Or, if you have a Pico with the male headers already soldered in (Pico H), you can plug in the Pico to set the socket spacing and alignment while you solder the first pins. Solder one pin on each side of the socket, then check alignment before soldering the remaining pins.

IMG_5367

When finished, it will look like:

IMG_5368

For the antenna, either mount the

  • SMA connector, X11 (not shown)
  • The chip antenna, E1, and a 0 Ohm jumper R28:

IMG_6667

  • Or cut a length of tape measure to be 1/4 wavelength of 434.9 MHz (shown here)

IMG_5370

Secure the tape measure antenna using the screw and the nut. The screw will cut threads as you turn it with pressure. Do not over tighten or the threads can get stripped.

IMG_5371

Next, install the stacking GPIO header J1:

IMG_5372

It is inserted on the bottom as shown here:

IMG_5373

Flip the PCB over and solder all 40 pins on the top, being careful not to let the solder climb up the pin.

IMG_5374

Next, install the 68 Ohm 1/2 Watt resistors R26 and R31. These resistors are fatter and longer than the other resistors since they have to attenuate the transmitter power. Also install the 180 Ohm R29.

IMG_5377

Solder one pin at a time on the bottom of the PCB and make sure they are inserted correctly. Then solder the other pin and trim the excess leads with side cutters:

IMG_5379

Here's how they look when they are installedL

IMG_5380

IMG_5381

If the SMD resistors R2 and R10 are not installed, install the 1k resistors R1 and R9. If the SMD resistors R23 and R25 are not installed, install the 4.7k resistors R20 and R22.

IMG_5382

IMG_5383

The CubeSatSim can now be tested in the FSK and BPSK modes. The Raspberry Pi Pico needs to be programmed first following these instructions:

  1. Download the latest .UF2 file here: https://github.com/alanbjohnston/CubeSatSim/releases
  2. Install it by following these steps:
  • Plug your Raspberry Pi Pico into your computer using the micro USB port while holding down the BOOTSEL button (white button on the Pico). It should mount as a drive RPI-RP2.
  • Drag the .UF2 file that you downloaded in step 1 to the Pico flash drive RPI-RP2.
  • You can monitor the serial output using Arduino or a terminal emulator such as PUTTY to see the log files or make configuration changes.

IMG_5385

You should receive a radio signal on 434.9 MHz. It will take a few seconds to power up. The built-in LED on the Pico will blink (unless you are using a Pico W which has WiFi - no LED will blink on this board) after a few seconds then stay on and blink off every 4 seconds or so. If you have a Ground Station with FoxTelem running, you can decode the packets. You can change modes by typing on the serial port (FSK is f while BPSK is b) or by pressing and holding the BOOTSEL button on the Pico (FSK is two blinks while BPSK is 3 blinks).

Install the Red, Green, and Blue LEDs LED3, LED4, and LED5, and the associated resistors R32, R34, and R35:

IMG_5386

IMG_5387

Solder the switch S1 and the RBF switch X1:

IMG_5388

Next if the USB-C connector J9 isn't already installed, install the Sparkfun USB-C breakout board, J8, using a 1x6 pin header.

IMG_5390

It is installed on the bottom of the PCB, but it is installed UPSIDE DOWN.

IMG_5391 2

Also, note that the solder mask covers the holes on the top of the PCB making the soldering a bit tricky. I'd recommend applying liquid solder and using a very small amount of solder to ensure that a good electrical contact is made. This image shows both the surface mount USB-C on the top, and the USB-C breakout board soldered onto the bottom:

IMG_5393 2

Install the capacitors C2 and C4 and resistors R3 and R8. C4 is an electrolytic capacitor that looks like a small can. It needs to be installed with the correct polarity. The PCB has a label for the + side, which is the upper pin in this photo. The capacitor itself typically has a label for the - lead, the shorter lead in this photo:

IMG_5394

IMG_5395

Now you can test in the APRS, SSTV, and CW modes. On startup and when changing modes, the built-in LED on the Pico and the blue LED will blink when the CW ID is transmitted and you should hear it at 434.9 MHz FM.

IMG_5399

If you apply power to the USB-C connector at the top of the board, the red LED should illuminate. However, the Pico will not power up until diode D3 is installed in a later step:

IMG_5402

Next, install the STEM green and blue LEDs LED1 and LED2 and the associated resistors R13 and R14.

IMG_5404

Install the two diodes D3 and D7, being careful about the polarity.

IMG_5405

IMG_5406

These closeups show the correct polarity:

IMG_5408

IMG_5409

Install the diode D9 and 10k resistor R11 and capacitor C5. Install the right angle female socket J4 on the BOTTOM of the PCB.

IMG_5410

Note the correct polarity of the diode D9:

IMG_6679

IMG_5413

IMG_5414

The BME280 and MPU6050 sensors are mounted on the board through female pin sockets:

IMG_5415

Solder the female pin sockets on the PCB and solder the pin headers on the boards, with the longer pins facing out (down in this photo):

IMG_5416

With D3 in place, the Pico board can be powered through the USB-C connector and the battery board charged; the red LED will illuminate. With D7 in place, the micro USB connector on the Pico can be used to charge the Battery board as well.

IMG_5421 2

The ESP32-CAM camera can also be plugged into the socket on the bottom of the PCB

IMG_5424 2

Batt Board v0.2

Here is the Batt PCB v0.2:

And the schematic:

The battery board components are:

  • Batt PCB v0.2
  • Stacking GPIO header
  • 4 cell battery holder
  • mounting square
  • 4 NiMH AA batteries
  • zip tie

IMPORTANT NOTE: There is a JST 2.0 connector on the board but the new design supplies power through GPIO pin 4 so this connector is only needed for other uses.

IMPORTANT NOTE: If the RBF switch is not installed (or JP5 not cut) or the RBF pin not inserted, the Pico will power up when the Batt board is plugged into the GPIO header stack.

IMG_6576

Flip the PCB over to the bottom side and install the GPIO stacking header:

IMG_6579

Flip the PCB over the top side and carefully solder only the 4 pins on either side of the GPIO connector:

IMG_6578

Stick the mounting square on the PCB ready to mount the battery holder:

IMG_6580

Mount the battery holder on the PCB top:

IMG_6583

Flip the PCB upside down and solder the two pins:

IMG_6581

Trim the leads after soldering:

IMG_6582

Insert the 4 NiMH AA batteries:

IMG_6584

Check for a voltage around 5V with a multi meter set to DC voltage using the BAT+ and BAT- terminals on the top of the PCB:

IMG_6588

Secure the batteries with the zip tie:

IMG_6585

Cut off the tail of the zip tie after tightening.

Solar PCB v0.2

Here is the Solar PCB v0.2:

Here is the schematic:

cubesatsim-solar-0.2_schematic.pdf

The diodes D1 - D6 and resistors R3 and R4 are installed vertically: IMG_4617

Here is the polarity of the diodes:

IMG_4618

They are installed on the PCB top then soldered on the PCB bottom:

Trim the leads after soldering:

On the bottom, install the 1x4 pin header

IMG_4642 2

Use this pin header to test the INA219 boards before soldering and mounting them.

On the PCB bottom, install the GPIO header J1 and three 1x6 female sockets:. Alternatively, after testing the INA219 boards can be soldered directly without sockets.

updated

Flip the PCB to the top and solder.

IMG_4643

Install 3 INA219 boards on the bottom:

IMG_4644

Here they are installed. Set the jumpers as marked on the PCB.

IMG_4645

Install 12 JST 2.0 connectors on the top - there are two for each of the sides of the CubeSat. Apply a drop of superglue to the plastic before attaching them so they will hold together while plugging and unplugging cables:

IMG_4648

IMG_4651

DO NOT INSTALL a connector for the battery, as the power goes through the GPIO connector.

Install 4 female headers 1x6:

IMG_4652

Install 4 INA219 boards on the top:

IMG_4657

Here they are installed with the jumpers set per the markings on the PCB.

IMG_4667

Stacking the Boards

The stacking order is (from the bottom) Batt board, Pico board, Solar board.

The standoffs to use are M2.5. screws are used on the top and on the bottom through the bottom frame.

This image shows the hardware with the left side at the top:

IMG_6712

The standoffs at the bottom are 4 M2.5 15mm.

The standoffs between each the three boards are made up M2.5 20mm+6mm and M2.5 6mm+6mm. There are 8 of these.

The resulting stack looks like this:

IMG_6660

Camera

The instructions for the ESP32-CAM are here: ESP32 CAM for Pico

Frame

Here are the v2 Frame STL files: https://github.com/alanbjohnston/CubeSatSim/tree/pico/hardware/framev2

You need to print two of each.