[PIC] PIC Based ultrasonic oxygen purity analyser

[unhappy]

I am looking for Help in Designing Oxygen Analyzer using PIC16F887 + Ultasonic Oxygen Purity Sensor
Data sheet is attached herewith

 

[KlausST]

Hi,

Do you want someone of us to do your job and design the whole measurement device for you?
Or do you have a more detailed question?

You say you need help, but not in which regard.
Are you an absolute beginner not knowing what a resistor is or are you a an experienced designer but need help in getting the most possible accuracy?

Klaus

 

[Aussie Susan]

The data sheet shows that it uses a serial interface so you will need to use the UART in the MCU.
The MCU you are using can work at 3.3V (which is what your peripheral needs on the Rx and Tx lines) but that limits your oscillator to about 10MHz - probably not an issue for you but that really depends on what else you are trying to do.
If you want to have a 20MHz clock then you will need a 5V supply but that means the GPIO pins will want to work at that voltage as well - this implies you should use a voltage level translator on these lines.
Of course this all depends if you are creating a commercial product (in which case I suspect you don't have the experience to tackle this right now) or if it just a hobby project (in which case I suggest that you get a lot more experience with embedded systems before you start).
The data sheet is clear on the various commands and responses you use to communicate via the UART.
You probably also need a display of some sort. Be careful NOT to select one that uses a UART as the MCU you have selected only has one which you will need for the oxygen device. There are LCD displays (for example) that use the SPI or parallel interfaces but again make sure that you don't run out of pins/modules.
I strongly suggest that you start small - learn to flash a LED (that will teach you about how to set up the clock, the I/O pins, programming the device etc.), then use a UART to send and receive characters with a PC. then get the display to work and finally connect to the oxygen device.
Whatever you do, remember that you only have 8K of FLASH memory, 368 bytes of RAM (and 256 bytes of EEPROM) do you can't fit much in there.
Susan

 

[kgavionics]

You didn't specify what kind of programming language you want to program this MCU! Bear in mind, that the 16F family are not optimized for C language (because of the limited stack pointer size)!
Why you don't go with an Atmega328? They are cheap, designed to be used with C language?

 

[Aussie Susan]

@kgavionics - what the OP is asking is perfectly possible with the chip he has specified and using C (the C compilers know the limitations of the chip and take those into account, sometimes by using a soft stack).
I certainly think that a PIC18F device would be more suitable or even one of the more modern PIC16 devices. While the Atmega (in fact you can list just about any other MCU you like) would also work, there is nothing really wrong with the OPs choice.
We really need to hear back from the OP to see what (s)he has tried, what has worked, what doesn't etc. before we can provide much more assistance.
Susan

 

[kgavionics]

@kgavionics - what the OP is asking is perfectly possible with the chip he has specified and using C (the C compilers know the limitations of the chip and take those into account, sometimes by using a soft stack).
I certainly think that a PIC18F device would be more suitable or even one of the more modern PIC16 devices. While the Atmega (in fact you can list just about any other MCU you like) would also work, there is nothing really wrong with the OPs choice.
We really need to hear back from the OP to see what (s)he has tried, what has worked, what doesn't etc. before we can provide much more assistance.
Susan

You are totally right, Susan ! Excuse if I'm a bit biased to the AVR chips!

 

[unhappy]

Thank-you to all for replies .Chip doesn't matter as long as it's not costly

 

[Aussie Susan]

Chip doesn't matter as long as it's not costly

Yes and no. You need to consider the entirety of your application. All you have mentioned so far is that you want to connect to a particular chip that uses a UART serial interface.
What else do you want to do? Display information on a LCD? Store data for months/years in a way that survives power failures? connects to something via WiFI, USB, Ethernet? Performs complex calculations?
Once you have considered al that the complete system has to do, then you an determine a suitable MCU with the required modules, memory etc..
Also this you need to consider what you consider 'costly'. For some, this might be a few cents, or dollars, or 10's of dollars etc. Also the cost of the MCU is often not the most costly part and scrimping a few cents on the MCU might end up costing more than you save.
Also if this is for a hobby, then you might be able to reuse the parts when you have finished. If this is for a commercial products, then cost might be an issue but so it reliability, perhaps 'in field' firmware upgrades, repairability etc..
Susan

 

[unhappy]

Yes and no. You need to consider the entirety of your application. All you have mentioned so far is that you want to connect to a particular chip that uses a UART serial interface.
What else do you want to do? Display information on a LCD? Store data for months/years in a way that survives power failures? connects to something via WiFI, USB, Ethernet? Performs complex calculations?
Once you have considered al that the complete system has to do, then you an determine a suitable MCU with the required modules, memory etc..
Also this you need to consider what you consider 'costly'. For some, this might be a few cents, or dollars, or 10's of dollars etc. Also the cost of the MCU is often not the most costly part and scrimping a few cents on the MCU might end up costing more than you save.
Also if this is for a hobby, then you might be able to reuse the parts when you have finished. If this is for a commercial products, then cost might be an issue but so it reliability, perhaps 'in field' firmware upgrades, repairability etc..
Susan

Sorry friends For Responding late as I was busy in Family Medical problems. I will be using two pressure sensors and 4digit SSD LED display or 1602 LCD graphics Dis and Yeah I would Prefer PIC16F series PIC18F also is OK for me

 

[Aussie Susan]

It seems that you have changed from using an oxygen purity sensor to using two pressure sensors.
Also I take it that you only want to display the current value(s) on a display so there is no storage involved.
For a 4-digit SSD LED display you will need either 12 IO port signals or some external shift registers that you will need to drive with fewer pins. I assume the '1602 LCD display' is one with a 'standard' HD44780 interface chip in which case you will need at least 6 IO port signals.
The PIC16F877 should have enough I/O ports for either display. However that may not be the end of the story.
What are the pressure sensors you want to use? More specifically what sort of interface do they use?
Is this a stand-alone system in which case you will need a battery of some sort. What is the required minimum life of the batteries - this may have an impact on the devices you chose due to their current draw.
Alternatively will this device be plugged in to a power supply?
These are some of the high level design decisions you need to think about for your design.
Susan

 

[Dan1138]

It's hard to know for sure but the Original Poster(OP) seems to be looking from someone to do the design work for a school project.

The components the OP has selected:

• PIC16F887
• GASBOARD-7500H
• 1602 LCD character module
• or 4-digit 7-segment LED module.

If this is a school project the OP needs to try to write a detailed description of how the parts are to be physically connected together.

An overall description of how a person is to use the device is essential.
This description should include things like:

• description of what the device looks like
• how to connect the device
• how to select data to be displayed
• how to calibrate

Anyone that posts here asking for design help needs to at the very least try to do these thing.

Someone that does not try does not deserve help.