Conclusion: BOM (electronics only)
For more information on the design process of the schematics go to this page for V1 and this page for V2.
I THINK THE PACKAGING TYPES ARE NOT QUITE THE SAME YET AND DO NOT CORRESPOND WITH THE FOOTPRINTS. TODO: CHECK (AND FIX) THAT
| Circuit | Component Name | Quantity | Octopart | AliExpress | Other |
|---|---|---|---|---|---|
| Pico | Pico Zero RP2040 | 1 | 14.19€ (10 pcs) | ||
| UI | (Arcade) button | 1 | 0.99€ (28mm, rgb) | ||
| UI | R 150Ω | 5 | 0.07 $ | 0.93€ (50 pcs) | |
| UI | R 120Ω | 5 | 0.1$ | 0.55€ (100 pcs) | |
| UI | R 75Ω | 5 | 0.06$ | 0.99€ (20 pcs) | |
| RFID+UI | C 100uF | 5 | 2.44$ | 0.99€ (50 pcs) | |
| RFID | CEG006900 | 4 | 7.29€ (10 pcs) | ||
| BAT | Charging module with protection | 1 | 0.27€ | ||
| BAT | Coin Battery Holder | 1 | 0.35$ | 0.24€(10pcs) | |
| BOOST3.3V+5V | L 10uH | 3 | 0.08$ | 0.99€ (50pcs) | |
| BOOST3.3V | ADP161 | 1 | 1.06€ | 1.06€ | |
| BOOST3.3V | R 360k Ohm | 1 | 0.004$ | 0.67€ | |
| BOOST3.3V | R 180k Ohm | 1 | 0.017$ | 0.67€ | |
| BOOST5V | C 15uF | 1 | 0.051$ | ||
| BOOST5V | C 470uF | 1 | 0.178$ | 0.99€(10pcs) | |
| BOOST | 1n5819 | 1 | 0.077€ | ||
| BOOST | MC34063AP | 1 | 0.274$ | 0.99€ (10 pcs) | |
| BOOST | C 100uF | 1 | 2.44$ | 0.99€ (50 pcs) | |
| BOOST | R 0.33Ω | 1 | 0.34$ | ||
| Total cost per robot | € | ||||
| Total cost for 10 robots | € | ||||
| Total cost for 100 robots | € | ||||
| Battery excluded |
RFID-RC522 module vs self design of same module
While I was already assembling components for the project, I stumbled upon a schematic that explained how to build the RFID-RC522 module. If I can lower the total costs that can be great. So, here is a comparison:
| Criteria | Assembled RFID RC522 | Nodule based on RC522 |
|---|---|---|
| Cost (10 robots) | 7.389€ | |
| Electronic simplicity | Plug and play | Long time to create |
=> Result: buy assembled RFID module
Table to calculate the costs of a bought rfid rc522 module
| Circuit | Component Name | Quantity | Octopart | AliExpress | Other |
|---|---|---|---|---|---|
| RFID | 1 | - | 7.29€ (10 pcs) | ||
| RFID | C 100uF | 1 | 2.44$ | 0.99€ (50 pcs) |
The costs will not be cheaper than that. Thus, I will end this comparison here.
Low noise boost Converter to 3.3V
| Circuit | Component Name | Quantity | Octopart | AliExpress | Other |
|---|---|---|---|---|---|
| BOOST3.3V | L 10uH | 1 | 0.08$ | 0.99€ (50pcs) | |
| BOOST3.3V | ADP161 | 1 | 1.06€ | 1.06€ | |
| BOOST3.3V | R 360k Ohm | 1 | 0.004$ | 0.67€ | |
| BOOST3.3V | R 180k Ohm | 1 | 0.017$ | 0.67€ |
Boost Converter to 5V
| Circuit | Component Name | Quantity | Octopart | AliExpress | Other |
|---|---|---|---|---|---|
| BOOST5V | C 15uF | 1 | 0.051$ | ||
| BOOST5V | L 10uH | 2 | 0.08$ | 0.99€ (50pcs) | |
| BOOST5V | C 470uF | 1 | 0.178$ | 0.99€(10pcs) | |
| BOOST | 1n5819 | 1 | - | - | 0.077€ |
| BOOST | MC34063AP | 1 | 0.274$ | 0.99€ (10 pcs) | |
| BOOST | C 100uF | 1 | 2.44$ | 0.99€ (50 pcs) | |
| BOOST | R 0.33Ω | 1 | 0.34$ |
Charging System
LiPos can explode quite easily! They also provide a lot of amperage and are rechargeable. To ensure safety and effectiveness, both a reliable Charger IC and a protection module are important.
To compare, the same circuit assembled costs 0.27€. I most likely will not be able to make it any cheaper, so I'll go with that! It will also save a lot of time in the production process.
Quest to find a suitable battery
Requirements: cheap, small, rechargeable. Type: LiCoCO2 or LiMn. Voltage: Ideally 3.7V. Amperage: mind 190mAh (for circuit 174mAh + min. button 20mAh)
Possible batteries:
- 2.48€ CR2032 220mAh Lithium Camelion
- 11.89€ CR2032 (5pcs) 230mAh Lithium Varta (single battery 2.378€)
| Circuit | Component Name | Quantity | Octopart | AliExpress | Other |
|---|---|---|---|---|---|
| BAT | Coin Battery Holder | 1 | 0.35$ | 0.24Euro(10pcs) |
User Interaction
Decision: 1 RGB LED Arcade Button
| Circuit | Component Name | Quantity | Octopart | AliExpress | Other |
|---|---|---|---|---|---|
| UI | (Arcade) button | 1 | 0.99 (28mm, rgb) | ||
| UI | R 150Ω | 5 | 0.07 $ | 0.93€ (50 pcs) | |
| UI | R 120Ω | 5 | 0.1$ | 0.55€ (100 pcs) | |
| UI | R 75Ω | 5 | 0.06$ | 0.99€ (20 pcs) | |
| RFID | C 100uF | ? | 2.44$ | 0.99€ (50 pcs) |
5 RGB LEDs vs 15 single LEDs vs 5 Neopixel
There are many ways to light up a project with endless colors. Originally, I was working with RGB LEDs but found the pin usage quite high. After researching about Charlieplexing and Common cathode networks, I did not quite feel comfortable with the idea of using said principles because I have not fully understood how they work. A RGB LED can be modelled as 3 single LEDs. Which one is better? In both cases, neither the programming nor the wiring is messy. Benedikt from the LAB suggested to look into the Neopixel as a possible alternative.
Eventually, I remembered to base my decision on facts. So, here is a table that will help choose 1 option.
| Criteria | 5 RGB LED | 15 Single LED | Neopixel |
|---|---|---|---|
| Color options | all | limited | all |
| Simplicity (electronic) | no | absolutely no | yes |
| Simplicity (programming) | medium | medium | medium (through a library) |
| Cost | 0.358$ (Octopart), 0.99€ (50 pcs) (AliExpress) | 0.99€ (LED Pack 100pcs) (AliExpress) | 5.36€ (10 pcs) (Berrybase) |
=> Result: will use RGB LEDs
5 RGB LEDs vs 1 RGB LED
UI = User interface; BOOST = switch boost module; BAT = battery
Note: $ and € will be counted one to one. The cheapest option is the one considered when calculating the total costs.
Here I choose the switch boost converter to step-up the voltage to 5V to power the LEDs for the user interaction. The reason why I compare the 5 RGB LED configuration against the 1 RGB LED configuration is because the 5 RGB LED constellation would allow for a finer presentation of the games with less robots. However, the amperage consumption skyrockets when adding more LEDs. Hence, the cost will be the deciding factor: finer segregation vs fewer robots.
5 RGB LED configuration
| Circuit | Component Name | Quantity | Octopart | AliExpress | Other |
|---|---|---|---|---|---|
| UI | R 120Ω | 5 | 0.1$ | 0.55€ (100 pcs) | |
| UI | R 150Ω | 5 | 0.07 $ | 0.93€ (50 pcs) | |
| UI | R 75Ω | 5 | 0.06$ | 0.99€ (20 pcs) | |
| UI | PNP Transistor | 3 | |||
| UI | (Arcade) button | 1 | 0.99 (28mm, rgb) | ||
| UI | RGB LED | 4 | 0.358$ | 0.99€ (50 pcs) | |
| BOOST | L DO3316P-472 | 1 | - | 1.14€ | |
| Schottky Diode MBRD835LT4G | 1 | 0.922$ | 3.69€ (10pcs) | 1$ | |
| LT1370CR | 1 | 12.32$ | 4.39€ | - | |
| R 18.7kΩ | 1 | 0.0007$ | 0.99€ (100pcs) | ||
| R 6.19Ω | 1 | 0.099$ | 0.99€ (100pcs, 6.2kΩ) | ||
| R 2kΩ | 1 | 0.099$ | 0.99€ (100pcs) | ||
| C 100uF | 2 | 2.44$ | 0.99€ (50 pcs) | ||
| BAT | Sony Li-On 3.7V 3120mAh | 1 | - | - | 7.5€ |
Total Cost without battery: 7.6761€(per robot), ???€(for 10 robots)
1 RGB LED configuration
| Circuit | Component Name | Quantity | Octopart | AliExpress | Other |
|---|---|---|---|---|---|
| UI | (Arcade) button | 1 | 0.99 (28mm, rgb) | ||
| BOOST | 1n5819 | 1 | - | - | 0.077€ |
| BOOST | MC34063AP | 1 | 0.274$ | 0.99€ (10 pcs) | |
| BOOST | L 2.2uH | 1 | 0.376$ | 0.64€ (10 pcs) | |
| BOOST | C 100uF | 1 | 2.44$ | 0.99€ (50 pcs) | |
| BOOST | C 220uF | 1 | 2.44$ | 1.99€ (10 pcs) | |
| BOOST | C 470pF | 1 | 0.042$ | 0.99€ (100 pcs) | |
| BOOST | R 0.33Ω | 1 | 0.34$ | ||
| BOOST | R 120Ω | 5 | 0.1$ | 0.55€ (100 pcs) | |
| BOOST | R 75Ω | 5 | 0.06$ | 0.99€ (20 pcs) | |
| BAT | Flywoo Explorer | 1 | 25.95€ (4 pcs) |
Total Cost without battery: 1.8537€(per robot), 15.137€(for 10 robots)
=> Result: 1 RGB LED configuration
Linear Buck Converter (not in there anymore)
I chose a linear buck converter to provide a constant 3.3V output to the RFID modules, which do not function properly if there is too much noise.
List of all components required
| Circuit | Component Name | Quantity | Octopart | AliExpress | Other |
|---|---|---|---|---|---|
| BUCK | AMS1117 | 1 | 0.036$ | 0.99€ (20 pcs) | |
| BUCK | C 100pF | 2 | 0.21$ | 0.99€ (20 pcs) | |
| BUCK | C 10 uF | 2 | 0.172$ | 0.99€ (30 pcs) |