If you have a CubeSatSim v1.0, v1.1, or v1.2, you can upgrade it by building a new STEM Payload v1.3 board and replacing your STEM Payload Board.

The STEM Payload upgrade board looks like this:

If instead you want to build a v1.3 CubeSatSim, follow these v1.3 CubeSatSim Instructions

If you already have the v1.3 STEM Payload board built and just need to install it, skip to this step.

Build the Board

Here's what you need:

• STEM Payload Board with SMT parts installed (or, at a minimum, U6 the FM Transceiver module and R3 or R4, a 1k resistor) Note that the USB-C J9 and the LPF do not matter if they are present.
• The parts listed on this Bill of Materials (BOM): https://docs.google.com/spreadsheets/d/1Ta5UaJcinGozcheROrkfwXdGSDUZrXvQ1_nbIBdIIOY/edit#gid=763146660 Make sure you select the "STEM Payload Upgrade" tab (sheet) at the bottom.

Here is the complete set of parts:

Video

Here is a video showing the assembly steps

Steps

Start with the PCB with the minimum SMT parts installed:

There are two jumpers on the bottom that you need to bridge with a blob of solder and one to cut. First, solder JP6. Here's how it looks before:

And after adding a solder blob to bridge (short) it:

You should also bridge JP7 to connect the FM Transceiver to your existing antenna and cut JP3. If you want to use a separate antenna for your FM, install the SMA or tape measure antenna on X2. Note that you will need to modify your frame to mount this antenna since the V1 frame only has mounts for one antenna. You could, for example, print a new frame top which has two SMA holes.

Here are some soldering tips:

• Look for the outline of the part on the PCB before you install it. If you don't see a marking, it might mean that the part is installed on the other side of the PCB! (On this board, only J1 the GPIO header is installed on the bottom of the PCB. All the other parts are installed on the top of the PCB - the side with the AMSAT log on it).
• Always solder only one pin first. Then carefully check to see if it flush with board and straight and the right value. If not, you can apply more heat and move it around. Once you have installed more than one part, this becomes much more difficult.
• You can use the check boxes on the BOM to keep track of the parts you have installed.
• Some parts, such as diodes, electrolytic capacitors (cans), and Light Emitting Diodes (LEDs) have a polarity - check this carefully!
• Carefully check the color bands for resistors. You can use this handy calculator: https://www.hobby-hour.com/electronics/resistorcalculator.php If in doubt, measure the resistance in Ohms with your multi-meter!

Start with the two 68 Ohm resistors R13 and R15 (big 1/2 Watt resistors with color bands blue gray black) and the 180 Ohm resistor R14 (color bands brown gray brown) in the attenuator circuit. Note that if you are building a HAB payload, instead of installing them, bridge JP2.

All the resistors and diodes are installed vertically on the PCB, so they all need to have the leads bent over as shown. Insert the three resistors in the top of the PCB, then bend the leads on the bottom slightly so they are held in place:

Solder one pin on each resistor, then flip the PCB over and check to make sure they are fully inserted and straight:

Then solder the other pin:

Then trim the leads with your side cutters:

Here's how they look installed:

Next, install the audio low pass filter that feeds the PWM (Pulse Width Modulation) audio signals into the FM Transceiver module with 4.7uF capacitor C5 (can), 100nF capacitor C6 (small yellow capacitor), 200 Ohm resistor R20 (color bands red red brown) and 100 Ohm resistor R19 (color bands brown black brown)

Note that the electrolytic capacitor has a polarity. The shorter lead is labeled with a white - on the can. The longer lead is the positive, as shown here:

Here's how they look installed:

Here's the PCB on the bottom:

Next, install the two 4.7k Ohm resistors R23 and R24 (yellow violet red color bands):

Here's how they look installed:

Next we will install the 10k resistor (black brown orange color bands) R27, 100nF capacitor C9 (small yellow capacitor), and 1N4148 diode D3 (has a glass case with the numbers "41" and "48" written on it and a black band to indicate polarity) at the lower left corner of the PCB.

Note that the diode D3 has a polarity marked by a black band on the right lead here:

Here's how they look installed:

Next we will install the blue LED2 and 100 Ohm R30 (brown black brown color bands). Note the LED has a polarity. The longer lead is the positive, as marked here. The positive pin is away from the edge of the PCB where the PCB has a + marked.

Next install the green LED1 and 1k Ohm R29 (brown black red color bands). Again, note the LED polarity with the longer lead positive and mounted away from the edge of the PCB.

Here's how it looks installed:

Next, we will install the two 1x20 pin female sockets J2 and J3 for the Raspberry Pi Pico to plug into. These must be installed vertical and straight and the right distance apart, otherwise, the Pico will not plug in. Use the 1x8 male pin header from the MPU 6050 to achieve this, as shown here:

Flip the PCB over the the bottom and solder one pin on each header. Then check to make sure the headers are fully inserted, straight, and the right distance apart:

Solder the rest of the pins.

Next we will install the BME280 sensor (small purple board) J5 and MPU6050 gyro J4 (larger blue board). They can be soldered in directly using the male pin headers, or they can be installed in sockets. If you install them directly, insert the pin headers with the long side into the PCB.

First, we will install the female sockets for each sensor. Use blue putty to hold the socket straight and vertical:

Solder one pin on the bottom, then flip the board over and check the socket for insertion and straightness. Then solder the rest of the pins.

Insert the male pin headers into the sockets, long pins down:

Then mount the sensors on the pin headers and support with blue putty so it is straight and level:

Solder the pins on the top:

Finally, install the 2x20 female header J1:

It is inserted on the bottom of the PCB and soldered on the top:

Solder one pin on each side and check to make sure it is fully inserted and straight:

Then solder the rest of the pins.

Finally, install the Qwiic connector using the 1x4 male pin header. First insert the 1x4 header into the top of the PCB, long pins down:

Solder the pins on the bottom. Then, put the Qwiic connector board on top, using blue putty to hold it straight and level:

Finally, solder the pins on the top of the connector:

Here is the completed board:

Pico Software Install

Here is a video of this step.

Follow these steps to Install Software on Raspberry Pi Pico

Here's how it looks when you are programming the Pico through the micro USB cable:

Pi Zero Software Upgrade and Testing

Here is a video of this step.

Now we will upgrade the software in your Pi Zero to v1.3.

Your Pi Zero will need to have access to the internet to update the software. If you haven't connected your Pi Zero to your WiFi, you will need to do so. An easy way is to run the command sudo raspi-config then select System Options and then Wireless LAN to set your SSID and password. You may also need to set your country for WiFi to work. That is under the Localization Options in this same menu.

Log into your Pi then type these commands:

cd

cd CubeSatSim

git checkout master

git pull

git checkout beta-v1.3.1

./update

The new software should then be running after a reboot.

Unplug your old STEM Payload Board and plug in the v1.3 one.

The existing functionality of your CubeSatSim should still be there. You can verify this with the CubeSatSim Test Plan

Run the Upgrade Test Plan to verify the new functionality:

These steps assume your CubeSatSim is in APRS mode 1 to start. If you are in a different mode, jump to the step below that says "When in" for that mode.

:white_square_button: APRS mode uses the FM transceiver board but only sends a packet every 30 seconds

:white_square_button: You can change the mode of your CubeSatSim to FSK (mode 2) using an FM carrier transmitted at 435.0 MHz as the APRS packet is transmitted and for a few seconds after. The green LED will blink twice briefly when the command is received and the blue LED will go off. The CubeSatSim will reboot, and after about 30 seconds begin transmitting in FSK mode.

:white_square_button: If you run FoxTelem, you should see the "Payload OK" listed under Experiments, and the sensor data displayed and you can see the Ground Commands count displayed in the Computer Software box. Note that it only increments with RF commands not command line commands.

:white_square_button: When in FSK (mode 2), you can transmit an FM carrier at 435.0 MHz for a few seconds and change the mode to BPSK (mode 3). The green LED will blink three times briefly when the command is received and the blue LED will go off. The CubeSatSim will reboot, and after about 30 seconds begin transmitting in BPSK mode.

:white_square_button: When in BPSK (mode 3), you can transmit an FM carrier at 435.0 MHz for a few seconds and change the mode to SSTV (mode 4). The green LED will blink four times briefly when the command is received and the blue LED will go off. The CubeSatSim will reboot, and after about 30 seconds begin transmitting in SSTV mode.

:white_square_button: SSTV mode uses the FM transceiver board. Camera images (not stored) display your callsign and the battery voltage and current (simulated battery voltage and current are not displayed) in black text

:white_square_button: When in SSTV (mode 4), you can transmit an FM carrier at 435.0 MHz for a few seconds after an image transmission has just completed, and change the mode to CW (mode 5). The green LED will blink five times briefly when the command is received and the blue LED will go off. The CubeSatSim will reboot, and after about 30 seconds begin transmitting in CW mode.

:white_square_button: CW mode uses the FM transceiver board.

:white_square_button: When in CW (mode 5), you can transmit an FM carrier at 435.0 MHz for a few seconds after a CW frame has just completed, and change the mode back to APRS (mode 1). The green LED will blink once briefly when the command is received and the blue LED will go off. The CubeSatSim will reboot, and after about 30 seconds begin transmitting in CW mode.