Suggestion** Microcontroller+ RF module for Capsule Size circuit

[zetinal34]

Suggestion** Microcontroller+ RF module for Capsule Size circuit (Pill size)

Hi all,

I am currently doing the project on gas sensor capsule. (swallowable)
I'm very new to micro-controller and rf module.
I really need help and advice on what micro-controller and transceiver I should use for this project

The requirements are as below
-Small dimension, Pill size (Both micro-controller and transceiver)
- Low power
- Transmission frequency = 400MHz band (It is safe for human tissue as I know, I'm not sure 2.4GHz will be ok or not)
- be able to control and manage data from sensors (around 4 sensors)

From the research I did, I found that there are some system on chip (SoC) available. It looks convenient, However, it can't be program unless I have the development kits. I only have budget around $200 which is not enough for some development kits. (Please advice if there is other way)

Can someone please give recommendation for the chips in this case? I have done some arduino project, so I'm familiar with C/C++, it would be better if I can develop using C language.
Please let me know if there is any different approach.

Any advice is welcome and appreciated.

Thank you very much.

 

[Nidin]

Hi buddy,

U can use PIC16F877A and Transceiver 27982.

Browse in microchip for the micro controller and in Parallax.com for the Transceiver. The PIC16F877A can be programmed in C or mikrobasic.

Best of luck.

 

[zetinal34]

Hi man,

Thx for you suggestion but I need them to be really small for the capsule size, like PillCam

Anyway thank you man.

 

[Nidin]

Sorry buddy.

Didn't saw the Capsule size circuit

 

[sky_123]

What is the power source?
If it is a small watch-battery type of cell (I think they get as small as 4 or 5mm diameter) then you could use it to power an atmel ATtiny
device (which even comes in 6-pin versions). And I think it has an ADC for a sensor. For the transmitter, you could use a SOT-23 (or smaller) transistor as a single-transistor oscillator (google for colpitts oscillator).
It could probably all fit in 1cm cube size or smaller, but I wouldn't swallow a battery ; )
For the development environment, clones of Atmel device programmers are typically just in the tens of dollars price range and the dev environment can be downloaded for free.

 

[zetinal34]

Thank you for your advice.


I'm really new to these things and I find that it is quite hard for me to implement a whole new PCB and test it.

Is there any product which has the development tool for this kind of project? Maybe Micro controller development kit with transmitter module?

I really like your suggestion but is there a way that is not so manually as it will be really tough for me, I know very little about micro controller integration. Is there anywhere I could read to get started.

*For ATtiny, I can use this prototype board to program it right? https://www.sparkfun.com/products/33 and I could integrate transceiver to this board? Any suggestion?

** I found this product from TI **broken link removed** , I wonder is it suitable for my project? I don't see people talking about it much though.

Thank you very much

 

[sky_123]

That ATtiny board would probably be fine. Looks like someone has written instructions on how to use it, with a programmer: **broken link removed**
There is enough space on that board to also have a single-transistor oscillator, e.g. a colpitts. Alternatively, you could just use a tiny oscillator module, like this one,
which is 5mmx3.2mm: https://www.onsemi.com/pub_link/Collateral/NBVSBAXXX.PDF
There will be a lot of harmonics but maybe that is ok, since you might be able to have a smaller antenna for a higher freq.
You could connect the output to a small antenna. Ideally you'd want to have a matching circuit between the oscillator and the antenna, so if you have space, something like a transformer would be nice, e.g. https://www.minicircuits.com/pdfs/TC4-1T.pdf (connect the primary to pins 4 and 5 of that onsemi oscillator, and the secondary to some very small antenna).
You could use the ATtiny to switch the oscillator on/off, to generate a stream of information that could be received by a scanner radio tuned to the correct frequency.

 

[zetinal34]

Hi,

I happen to have https://www.es.co.th/Schemetic/PDF/TWS-BS3V1.01.PDF transmitter.

Is it ok for this transmitter to integrate with ATtiny board? It could save me a lot of time from making my own transmitter.

Thank you very much

 

[sky_123]

It looks a bit large to swallow. The onsemi oscillator is maybe 15 times smaller. But functionally the larger one should be fine too.

 

[zetinal34]

I'm about to order already but I got some problem. That programmer is not available in Australia (no shipping here). So now I'm finding the alternative one, I found **broken link removed**. From the spec, it seems to be working with the dev board but I'm not so sure, what do you think? Or you have any alternative programmer recommended?

Also in this case, should I use ATtiny13 or ATtiny85, which one is more suitable? **broken link removed** and **broken link removed**

*This project is making a prototype so it doesn't really have to be swallow-able, however, I would try the oscillator method as you suggest too.

**Is there any basic programming guide for ATtiny for me to begin with as I have no experience at all...

Thank you so much

 

[sky_123]

Yes, I think that programmer should be ok with ATtiny, but try to check if it handles the newer devices, in case the ATtiny85 is a new model. I've not used that programmer (I've used the AVR-ISP MK2 programmer) but I think they all work the same way. I've not used the ATtiny85 variant, but it looks nice. You might want the 'V' suffix version, it can operate down to 1.8V, so ideal for battery powered devices.
Regarding programming, you'd need to learn a little C programming, but not much. You can download for free the tools - you need a compiler (from iar.com) called IAR Embedded Workbench for AVR Kickstart version, which is a free 'C' compiler. You may also need AVR Studio from atmel.com, which might get used with that programmer, once you have compiled the code.

If you want step-by-step instructions on how to use the compiler, and to see an example program which turns on an LED when a button is pressed, you could **broken link removed** for the most part, although it is for a different Atmel device. The differences are little.

 

[zetinal34]

Just a little more question. Is it better to use AVR-ISP MK2 programmer? I find it somehow look better compare to the one I mentioned.
Since it has 6 to 10 PIN ISP, it will work with the board I chose earlier right? **I kinda confuse about ICSP and ISP, they are the same thing right?

thank you

 

[sky_123]

AVR-ISP is one of the 'official' ones recommended by Atmel, but others should be fine too, lots of people seem to be using all sorts. And actually I had problems with the AVR-ISP USB model that I had with Windows 7 64-bit (although on forums other people were ok with it), so I had to revert to using my older AVR-ISP RS232 version, which works with a USB-to-serial converter with Windows 7 64-bit. The AVR-ISP comes with two cables, so you can choose to use the 6-pin or 10-pin, depending on what board you have. Unfortunately I can't comment about the other programmers, I've never used them.

 

[zetinal34]

Thank you for your advice

I have read this tutorial http://winavr.scienceprog.com/example-avr-projects/running-tx433-and-rx433-rf-modules-with-avr-microcontrollers.html and http://narobo.com/articles/rfmodules.html, which is kinda similar to my transmitter. The problem is that the chip I chose (ATtiny85/13) has 8 pin and I'm really can't find Tx or Rx Pin in the data sheet... I'm thinking it should be in that 8 Pin but I don't really know what the code name on each Pin represent(eg. PB1 (MISO/DO/AIN1/OC0B/OC1A/PCINT1)). Can you please point out where can I find out more about this and is the chip I chose actually has Tx and Rx?

Also with this transmitter, it has 8kbps data rate, will it be enough for gas sensor data? Assuming it is just normal gas sensor and the data will be transmitted to analyse later on in the process. It basically need to transmitted the raw data only.

** I have ordered AVR STK500 Compatible USB Programmer, the 8 pin development board, and the ATtiny13 and ATtiny85.
***I find that ATtiny2313 which has 20 Pins, provides Tx and Rx as the guide shows. Do I have to switch to ATtiny2313?

Thanks a lot for your help

 

[sky_123]

You're right, they connected the transmitter to the 'tx' pin of the microcontroller, but it is not essential for a simple sensor. Anyway, you need to decide what you wish to transmit, and the format. It could be as simple as a pwm stream corresponding to the value from than sensor for example. I suppose you also need something resistant to errors, in which case you may wish to (say) send the same value repeatedly, or continuously send a PWM stream. Or, you could save battery power and transmit nothing until a threshold has been exceeded, and then transmit an 'alarm' indicator? (I'm not familiar with gas sensors or the specific application you're considering). If it is just an on/off condition from the sensor, then maybe you just need to transmit pulses once the condition is reached/exceeded. If it is discrete values, then PWM could still be used, or if you are transmitting bytes, then you may wish to repeat them several times (or continuous stream) so that the receiver can receive it multiple times, in case there was a reception problem for some of the bytes. 8kbit/sec is possibly more than you need, if the conditions that the sensor is sensing are changing slowly, and if you don't mind that some longer time is taken to transmit the data. For example if you were sensing (say) temperature of a room, then a reading per second or per minute would be adequate, so 8kbit/sec is far more than needed for a room temperature application.
By using the 'txd' pin, they are able to use the microcontroller to automatically convert byte values into a bitstream. However there is nothing stopping you from writing your own code to convert the byte/value you wish to transmit into pulses, or just use pwm, on any general output pin on the microcontroller.