T3.x Flexiboard(?)

[Frank B]

Hi Tim,
TeensyTransfer works without problems, just use the right SPI Pins (the same as for Audioshield) and use a low FCPU

 

[Frank B]

How about adding a Nunchuk - Connector like this directly on Rev 0.2 ?



Nunchuks are cheap, i bought the last one for 4$ from china. It has a joystick, two buttons, and a 6 DOF IMU. Bus is I2C.

 

[Frank B]

Added Internetradio to examples:

https://github.com/FrankBoesing/FlexiBoard/tree/master/src/examples

 

[KurtE]

Hi Frank,

Looks like you are making great progress with your board!

I am playing around with my well monitoring board and may make a 2nd version to fix a few problems, or may not as so far simple to patch the board...

But was thinking of adding support for powering the backlight, instead of simply connecting it up through a resister to Vin.

So I was taking a look at your hook up and I see you are going through two transistors (BC850 and BSS138). I am trying to understand the need for both. My my last circuit analysis class was back in the ice ages, so most of the stuff I do on my boards is by example...

On some of my other boards I have used the BSS128, which i then feed into a larger transistor that enables power to servos...

The other example schematic I looked at was the Adafruit ILI9341 breakout board (https://cdn-learn.adafruit.com/asse...iginal/adafruit_products_schem.png?1395173896) and if I am reading it correctly it looks like they are using a MMBT12222 transistor.

Again please forgive my ignorance here as I still get confused on some simple transistor stuff, like when to use PNP vs NPN, FET vs Pipolar...

Thanks again

Kurt

 

[Frank B]

Hi Kurt, i'm currently working on v.02 - it will have much more features
The BC850 may not be needed - i'm not that expert, too (still very much electronic-noob, esp when it comes to analog..) . I'm waiting for a shipment of some FET FDV303 (Paul mentioned them). Looking at the datasheet, i think the additional T is not needed. So, for the next version I#ll remove the transitor (if the shipment from china does not need too long to be able to test...)

For v.01 i just wanted to make sure that it works i did not know the FDV303 that time..

EDIT: That Adafruit-Board uses 5V, correct ? I'm not sure if that is an issue or not..

Paul, can you help ? Would the FDV303N work, without Transistor ?

https://www.fairchildsemi.com/datasheets/FD/FDV303N.pdf

 

[KurtE]

Thanks Frank, will be interesting to see what all goes into your v.02

Will take a look at that Transistor... Also wondering if it would make sense to use something like the SN74LVT125, which I have used to drive Neopixels to +5v (think same as used on Teensy LC)

The adafruit board VIN can be 3-5v, I have a couple of them around that I use for experimenting as you you don't have to wire up things like TFT as it has the circuit in it. I think it is setup with that transistor, such that as long as you don't pull it low the backlight will work...

 

[Frank B]

I think, it will be - more or less - like this:


The nunchuck -connector needs some more work.

New:

- 3V3 Voltage-Regulator for Display + ESP8266 + "expansion port"
- Button-Battery
- USB-A
- Encoder
- Debug
- 0805 Parts
- FET for IR-LED (more power..)
- JEDEC-Memory on SPI1 (Display on SPI0)
- Less T3.2 compatibility

Hm, and there is still space for more...
I guess, i will order from China and will get 10 boards this time, so i have some spare. Any interests ? I will sell min. 4 of them, incl. some parts (USB-A, Battery-Holder, pogo-pins, Encoder, IR-LED...perhaps w25q128 flash+other SMDs)

 

[Frank B]

Kurt, so you're saying it works good with the Transistor you mentioned ?
Can the SN74LVT125 deliver enough mA ?

 

[KurtE]

Looks great,

As I mentioned, I am thinking of doing a slight revision of my similar board, mainly need to select the correct data pin for Interrupt... Already temporarily patched current board.

So if I did a new version, I was thinking what else I should do, things I found include:
a) Fix the LoRa pin
b) I have the socket for RTC battery, but I had etch running under it, which I don't like as don't want risk of short...
c) Thought I would add control over display backlight..., maybe also run IO pin to reset as well.
d) not sure if worth adding support to turn power off of Neopixel
e) I am also thinking of adding 3.3vVR for Display and LoRa. Probably an MCP1700, which I have used before.

So far I am trying to keep this board simple, but who knows may borrow a few more ideas...

 

[Frank B]

The MCP1700, which package do you use ?

Edit: I have some LM3940 on stock, so i will use them.

I've ordered these battery-holders:
https://de.aliexpress.com/item/20PC...32665933322.html?spm=2114.13010608.0.0.CeZJnv

Edit: And these Pogo Pins:
https://de.aliexpress.com/item/100P...6733.html?detailNewVersion=&categoryId=400103

Reset: I'll connect the DisplayReset to the Teensy-Reset this time.

 

[KurtE]

Kurt, so you're saying it works good with the Transistor you mentioned ?
Can the SN74LV1T125 deliver enough mA ?

Not sure again I have only used these for doing level shifting... Probably not, I think it only can do something like: 7 or 8 mA

 

[KurtE]

I have used the SOT89 versions in past, something like: http://www.digikey.com/product-deta...MCP1700T-3302E-MB/MCP1700T3302EMBCT-ND/652679

Battery Holder, I am using: https://www.digikey.com/product-det...tection-devices/BK-885-TR/BK-885-CT-ND/755448

 

[KurtE]

Reset: I'll connect the DisplayReset to the Teensy-Reset this time.

I think I read this earlier, but does it work to simply set up the Teensy-reset circuit to also go ti the DisplayReset line? Would be nice to not have to eat up another IO pin...

 

[Frank B]

Yup, works.

 

[Frank B]

Ok, i've ordered the boards from seeed. i wonder how long it takes (?) i hope, it arrives before x-mas.
I can only hope that the new backlight-fet will work (i'm still awaiting delivery), and that the drills for the pogo-pins are the right size
I decided to use "my" fat 1A voltage-regulator - because i have it on stock and it gives plenty enough power - more than USB can deliver.
It is used for extension on the big 2-row connector too (instead power from teensy)

 

[defragster]

What was the Seeed cost for how many boards?
The PCBS.io page still shows :: Ships From: Washington State, USA via USPS
So the new owner hasn't even gotten around to minor updates to the website. Hopefully they'll get up to speed and maybe be usable again - or better.

 

[Frank B]

The 10 boards (50mmx100mm) $11.92 plus $11.69 shipping (total $23.61). I could choose the color. I decided for blue.
Then, i've ordered parts...way too much I don't need to order USB-A connectors for the rest of my life

 

[Donziboy2]

Hello Frank, the 10K pull ups on CS, TS and DC. Are they a precaution or a necessity?