Hello to everyone.

I'm trying to create a phone or maybe a handheld based on FreeBSD. I'm not sure what the final form is. I would like it to be something like this,more or less :

https://ibb.co/99J6VrWv

The approach that I want to take is to use as many USB and HDMI peripherals as I can,so : a) HDMI screen is easily interchangeable. b) USB keyboard and touchpad (circle glidepoint touchpad :

https://www.cirque.com/glidepoint-circle-trackpads
)

c) portable battery

Now. What I want to do now is to convert the circle glidepoint touchpad into one USB device that can be recognized by any operating system,such as FreeBSD. Yes,because natively it is an I2C device.


I'm reading this guide to understand how to implement that layout.

https://beekeeb.com/cirque-trackpad-i2c-on-corne-keyboard/

At some point,he told :

5V

If you can power it with 2.5-3.6V, you can skip this section. The type-c breakout board runs at 5V. So we cannot directly power it directly. We can probably use a logic level shifter and voltage regulator to provide 3.3V. Alternatively, according to the post on Cirque Forum, the trackpad can run at 5V when R7 and R8 are removed.
Let's start saying that I won't remove any resistors,but I want to "a logic level shifter and voltage regulator to provide 3.3V"


With the help of some users of the various forums where usually I ask questions,I ended up creating this layout :


Radxa Zero-3W / USB-C 5 V ─usb- Seeed XIAO RP2040 (3 V3 MCU) ─ TXB0108/TCA9517
│ ▲ (shifts I²C or SPI lines to 5 V)
└─ 3 V3 REF ───────────────────┘
│
Molex 15164-0123 FFC │ 4-wire header
│ ▼
12-pin FFC Break-out PCB ───────── Cirque TM016016 (Ø 23 mm sensor)


Connection Cable / Board Notes

XIAO Shifter Dupont or Grove leads Lines at 3 V3 on MCU side
Shifter Break-out 4-wire header strip Lines now at 5 V
Break-out Sensor 30 mm 0.5 mm-pitch FFC Blue-latch socket already soldered


What I don't understand is how to connect the TXB0108 or the TCA9517 to the Seeed XIAO RP2040. I need to see it clearly and physically under my eyes. It's not enough for me to guess or try to understand it by reading some good sentences. Unfortunately I'm still a beginner.

I don't understand when the voltage regulator is needed and when it is not. For sure I don't want to shut it down or turn it up manually. My will is to keep attached and let it decide when it should be turned on or not.

Can the TXB0108 or the TCA9517 decide automatically when it is needed or not to run ? Can you suggest a regulator that decides by itself when it is needed or not ?

 

Maybe I found something that could work :

https://www.amazon.in/Step-down-Converter-DC8-2-32V-Transformer-Regulator/dp/B0CFHXWJH4

If it is useful,in Which link of the chain would it go into ?

 

This board works :

https://fingerpunch.xyz/product/svlinky

just because I can attach the 12-pin FFC connector directly to the board. It's good if the circle touchpad is 23mm. But for my FreeBSD cyberdesk I want to use the smaller version of their touchpads,at 16 mm. Now it comes the problem. The svlinky board does not accept a 6-pin FFC connector. So it should be recreated from scratch. Since it is open source,it can be done by some good engineer. What I want to know is how much money can cost to me to hire someone for this job.

 

Welcome to AAC.

Could you explain what the Xiao MCU is going to be doing for you? The Radxa Zero has the ability to do SPI/I²C and has plenty of GPIO.

Personally I would use DietPi, not FreeBSD on the Radxa as it is purpose built from Debian to deal with SBCs like the Zero and will simplify a lot of things.

Really, you don't provide enough detail to understand how you got to this point. Could you start by describing your problem rather than your attempt at a solution? Terms like "phone" and "handheld" don't describe what your requirements are, they just create a cloud of possibilities.

What will your device do?

What real constraints are you operating under? (not the arbitrary implementation choices you've already made, things like size, weight, runtime, cost, &c. that will drive the design)

If, for example, FreeBSD is a genuine requirement then add it to the list. If it is just something that you though was a good idea, don't—because it is very likely to cost time and effort to use, and may will limit what is possible.

 

Hello bro,

thanks for your help.

----> Could you explain what the Xiao MCU is going to be doing for you? The Radxa Zero has the ability to do SPI/I²C and has plenty of GPIO.

just because I don't want to make soldering on the boards nor using dupont fragile floating wires. I want that my system is plug and play,just it is if I use the svlinky board

---> Personally I would use DietPi, not FreeBSD on the Radxa as it is purpose built from Debian to deal with SBCs like the Zero and will simplify a lot of things.

Sure,but my project is about to create a FreeBSD "phone",not a Linux phone. FreeBSD is a must,simply because it is the OS I prefer.

--> What will your device do ?

I'm trying to creating a device that looks like a phone or a cyberdesk,that will allow to place and receive phone calls,rather than to be used as is,like a small pc. I do this as an hobby. I don't work for a company,so I don't have external constraints.