One Bluetooth transceiver with two 18M2 chips?

joe paul

Senior Member
Hi Folks,

A quick question, please!

With the 18M2, can 2 chips share one serial output from a Bluetooth transceiver?

Thanks!

Take care, Joe.
 

steliosm

Senior Member
For the serial-out from the BT module just make sure you have the grounds all connected together and I don't see any reason why it wont work.
Serial-in the BT module is going to give you troubles unless you use diodes in the serial-out pins on the 18M2.
 

joe paul

Senior Member
Hi Stelios,

Thanks for the reply and info! I only use the BT transceiver for one way traffic to the 18M2. That solves a lot of issues since I can always use more outputs or additional PWM pins. And I feel comfortable with the 18M2 chip.

Take care, Joe.
 

hippy

Technical Support
Staff member
As steliosm says; received data from a BT module taken to multiple PICAXE input pins should be perfectly okay with all 0V's connected together. It would be recommended to put current limiting resistors on the serial input pins in case any PICAXE input inadvertently becomes an output. 1K would probably be fine -

Code:
               ___    .--------------.
.-------.  .--|___|-->|In  PICAXE #1 |
|     In|  |          `--------------'
| BT    |  |   ___    .--------------.
|    Out|--^--|___|-->|In  PICAXE #2 |
`-------'             `--------------'
 

joe paul

Senior Member
Hi Hippy,

Thanks for the info, warning and the schematic. I like to be careful! I've been away from my Picaxe projects for a while and this idea flew into my head, but I figured I was missing some critical issue.

Take care, Joe.
 

erco

Senior Member
Yo Joe: I tried that with a pair of 08M2s a few months back and everything worked as expected (receive only).

You turned many of us onto RoboRemo a year or so ago, thanks for that reconfigurable app. Super, great for techies.

I've done a few BT projects for clients lately using Blue Control. It's a simple, free Android-only app which is NOT user configurable, just download & go. No settings to modify, accidental or otherwise. Better for non-tech clients from my experience, they can't get into trouble, plus they can easily download onto other devices.

https://play.google.com/store/apps/details?id=com.gundel.bluecontrol&hl=en

https://www.youtube.com/watch?v=3npXpqmQuwI
 

joe paul

Senior Member
Hi Erco,

Thanks for the info on the app and the link to your vids! I'll look into it. Many buttons to work with!

Take care, Joe.
 

Danielpbt

New Member
Hello, I have been analyzing your answer, and if I can understand it, maybe it can be useful for my project. I want to control two 28X2 from a HC06. I do not understand the scheme above. The HC06 has 4 pins, VCC, 0V, Tx and Rx (I only use the first three). I have them connected to the first processor (both mounted on an AXE020 board). I understood that I have to connect the 0V of both boards. I imagine that I have to remove two wires from the TX pin and send them as inputs to the plates. Is that so?
The solution I was thinking about, I put it as doubt in a new thread http://www.picaxeforum.co.uk/showthread.php?30683-Env%EDo-de-una-se%F1al-entre-dos- plates-AX-020 & p = 318872 # post318872. I have not received an answer yet. It's about a board being master and another slave, but I have not managed to make it work, nor do I know if it is possible to solve it like that.
Another possible solution that I have handled is to use two HC06, and from the tablet to connect at the same time to the two to send the signal. It seems that you can not connect to two HC06 at the same time. However, if you accept different types of Bluetooth devices together (for example, a mouse and a keyboard)
Thank you and apologize for my English
 
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