POV Clock- Need a way to wirelessly send messages

[gazmorganix]

I'm building a POV clock but one of the requirements is to be able to send a message to the clock to display while its spinning (around 10 characters).

We are planning to use a PIC microprocessor with c programming etc. The PCB hasn't been built yet but wondering what kind of device I could use to connect to the POV clock so I can achieve this? Ideally we would like to send a text to the POV clock and the short message is displayed.

Thanks

 

[moffy]

You could use a 433MHz Tx and Rx module or there is a bluetooth receiver module the HC-03 which is easy to interface (serial). You can then use an app on a phone of which there is at least one. Seen it done for the Arduino.

 

[gazmorganix]

I'm not using Arduino so would the HC-03 still work? I dont understand the TX RX module.

 

[dr pepper]

2 popular ways to do that.
1 use a infra red led and rceiver module.
2 presumably your using a rotary transformer or similar to transmit power to the device, well modulate the power line to send data, I have done this a couple of times, works up to a few hundred baud, I nicked the idea of velleman.

 

[Rich D.]

I vote for the IR LED method. It's simple to implement, just a couple of LEDs and resistors, and it should be quite easy to implement with a UART in the PIC.
It would help if you are familiar with creating/using an op-amp for a sensitive receiver amplifier though.
The 433MHz method has definite advantages, but you'll open a whole new can of worms unless you have done that before (and I haven't - and it's probably easier than I realize).

One might argue that the line-of-sight issue with IR LEDs is inconvenient. To that I would suggest making an "array" of LEDs and sensors - for example, if you want the transmitter to work from any angle, just pop in a few more LEDs on it facing different directions (at the expense of output power/battery power). You can do the same for the receiver if you wish. I had an old TV remote with multiple LEDs, worked great and I didn't have to think about aiming it as I ... select one:{lied / layed / laid / lazed} on the couch.

 

[dr pepper]

You can get easy to use rf modules, data in on the tx side and data out on the rx, howeverI think your right deciding to use infra red, dont bother makin a receiver, yo can get ready made modules with data out,I think tssop1738 is theone I've used, 5v in and data out with a pullip resistor, they need a good supply, a 100r resistor inline with +5v and a 100u cap in parallel should do it.

Directionality shouldnt be an issue, think about your remote for your telly, point in approximately the right direction and it works fine, as you say more leds gives you more o/p, if the room isnt totally black you'll be able to reflect the infra red off the walls.

 

[gazmorganix]

Ive decided to go with the IR and a few resitors etc and plug that into my PIC microcontroller. I was thinking of using an app to send the message from my phone (using the built in IR) to the IR on the POV clock. It this feasable? Any suggestions on how to make the app? Ie code types. Im a novice and have never written an app before!

 

[dr pepper]

Cant help you with the app, however the infra red rx need to be a irda module rather than a standard tv type receiver.

 

[gazmorganix]

Cant help you with the app, however the infra red rx need to be a irda module rather than a standard tv type receiver.

I'm using a TSOP 38238 IR receiver. Will this do?

 

[dr pepper]

Thats more of a standard tv remote type receiver, but if you allready have it connect it up to a supply and 'scope or logic probe the o/p it might work, however I suspect the data rate for irda is too high for it.

 

[gazmorganix]

Thats more of a standard tv remote type receiver, but if you allready have it connect it up to a supply and 'scope or logic probe the o/p it might work, however I suspect the data rate for irda is too high for it.

We haven't put the TSOP onto the pcb yet so I can still change it. What would you recomend instead? I dont understand what you mean by 'irda is too high for it.'

 

[gazmorganix]

If I go with Bluetooth, can someone recommend an actual device I can use? It has to be through hole as the PCB is through hole. And not arduino!!!

 

[dr pepper]

The data rate for irda is too high for a tv type ir receiver, irda has a minum rate of 9600 bits/s, tv remotes is around a 100 bits/s.

 

[cowboybob]

Bluetooth device:
https://www.sparkfun.com/products/12576?gclid=COTVo5rWgcICFfLm7Aod3RgAIw

Add some pins (holes are provided) for thru-hole connections to your PCB.

Arduino oriented, but still adaptable to any uC.

Not sure if or how rotation will affect comms:
From https://blog.shinetech.com/2014/02/17/the-beacon-experiments-low-energy-bluetooth-devices-in-action/
concerning a Bluetooth beacon device, this conclusion:

"Whilst interference is not playing a part in the beacon’s performance, rotation certainly is. It appears that the internal antenna must be favouring a particular direction, and this is having a major impact on the beacons. In a real world scenario it would be impractical to determine exactly which orientation each beacon should be facing for best performance. Further more, depending on how you are using your beacons you may need them to work through 360 degrees, so positioning of the antenna is irrelevant. This is just something to be aware of."