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https://github.com/faxm0dem/pi0tel

Last synced: about 1 month ago
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Host: GitHub
URL: https://github.com/faxm0dem/pi0tel
Owner: faxm0dem
Created: 2020-06-28T20:46:56.000Z (over 4 years ago)
Default Branch: master
Last Pushed: 2021-04-12T17:25:25.000Z (almost 4 years ago)
Last Synced: 2024-10-28T04:12:11.231Z (3 months ago)
Size: 1.1 MB
Stars: 5
Watchers: 2
Forks: 0
Open Issues: 1
Metadata Files:
- Readme: README.md

Awesome Lists containing this project

awesome-minitel - pi0tel - 3615 pi0, a Raspberry Pi pi0 or (Hardware / DIY Serial interface)

README

        # 3615 pi0

![3D Render of the pi0tel pcb](pi0tel-3d.png)

This uHat is designed to plug on top of a pi0 or pi0-w.

It's designed to plug to the DIN-5 at the back of a Minitel-2.

The pi0 will be powered by the Minitel through the Buck converter on

the hat. TX and RX will be level-shifted to the right level on the pi's UART.

The aim is to plug the resulting dongle into a Minitel, and get instant linux.

3615 pi0 (or shall we say, 31415 Minitel).

# Reference

* https://niteshbharadwaj.github.io/posts/raspi_from_battery.html

* http://pila.fr/wordpress/?p=361

* http://www.jelora.fr/post/2020/02/25/Adaptateur-prise-DIN-peri-informatique-Minitel-vers-Serie-RS232-et-Serie-USB.html

* https://www.ti.com/lit/ds/symlink/lm2596.pdf

* https://www.edn.com/pcb-layout-tips-for-thermal-vias/

* https://www.instructables.com/id/Arduino-to-RPi-three-ways-to-convert-5-volts-to-33/

* https://randomnerdtutorials.com/how-to-level-shift-5v-to-3-3v/

# Notes

* Cin and Cout

  - should both have short leads to lm2596

  - should both have low ESR (e.g. high V rating, Nichicon PL, 1.25*Vin = 10V)

  - Ripple current rating 50% of DC load (500mA in our case)

* Cin 270uF or 330uF

* Cout 470/25 Pana or 560/16 Nichi

* Diode

  - current rating = 1.3*load = 800mA

  - reverse V rating = 1.25*Vinmax = 10V

* Heat pad should at least be 0.4"²

* L choice see page 20 of Datasheet

  - L21/L22

||uH|A|SCHOTT|SCHOTT|RENCO|RENCO|PULSE|PULSE|COILCRAFT|

|-|--|-|------|------|-----|-----|-----|-----|---------|

|L21|68|0.99|67144070|67144450|RL-5471-5|RL1500-68|PE-53821|PE-53821-S|DO3316-683|

|L22|47|1.17|67144080|67144460|RL-5471-6|—|PE-53822|PE-53822-S|DO3316-47|

* If we want low output ripple we can add post ripple filter 1uH-5uH

  with low DC Resistance and low ESR cap