Selection of Microcontroller

[yousafzai82]

Hi all...

I am facing a problem with the selection of microcontroller. I need 2 analog inputs (12 bit adc) for two sensors and seven or eight digital inputs to take data from the already installed meters. Then i will send the data on USB Modem on remote server.

I am confused with frying of one channel for each sensor or i will have to use multiple ICs?

what about PIC18F4550 or ATMEGA8?

Please guide me to select right IC.

Zahoor Ahmad

 

[nandhu015]

ATMega8 have only 10 bit ADC and not 12 bit

Nandhu

 

[arbj]

the MCP3208/MCP3204 are 8 and 4 channel 12 bit ADCs from Microchip.

They use SPI for communication and need external Vref supply.

 

[wp100]

Hi,

You can have several different adc devices connected to one pic chip.

The 4550 chip is only 10 bit adc , think you will not find any chip in the 16 or 18F range that has 12bit adc and usb - you need a pic32 for that, unless you use a separate 12bit adc input chip.

 

[yousafzai82]

I have two questions if you can reply.

1)What about if i use 12 analog inputs of PIC18F4550 to one sensor and 13th 10 bit Analog input for another sensor. Will it work?

2) Will i be able to to send these two analog inputs along with 6 digital inputs with a single chip (i.e. PIC18F4550) using AT commands on the server?

 

[wp100]

Hi,

You are really trying to run before you can walk, you need to do a lot more reading up on micros in general.
What you are trying to do is a big complicated project and certainly not something I would expect a newbie to micros to be trying at this stage.


You have misunderstood the 12 bit adc term - it means that one adc input of a micro chip will read in the sensors output voltage as 0 - 5v max and present it to you as a 12 bit binary result , so a 5v input value would result in b' 1111 11111111'

 

[yousafzai82]

You are right in the sense that i am working with micros for the first time. But if i concertrate that would be tough and time consuming not impossible.

So it means i need Microcontroller with two ADC channels (AN0,AN1) and 6 digital inputs. I have to program it and send data using AT commands on USB interface. As i am using USB Modem.

If you can please tell me about a suitable microcontroller for the application in PIC32 or better to interface another Microcontroller (having USB) with MCP3202.
Being new to micros i am trying to have the least number of ICs on the package.

 

[wp100]

Hi,

Well you have to look at various aspects of your design as different things will dictate what you need.

Pic18 chips 10bit adc are standard dip plug in chips whereas the Pic32 are SMD parts which require expert assembly.

What is the reason for your 12bit adc ? does it need 12 bit or have you been tasked with that ? Can you use the more common 10 bit adc ?

USB is something you cannot program yourself, you use Microchips set code, which means you have to use Microchips C - are you familiar with that ?

You can avoid using USB in your programming, using the much simpler serial communcations and using a ready made serial to usb converter cable.

Again have a look at what your task really needs and what is available and what you feel you can achieve.
Learning to use C is a major thing in itself if you have not done it before.

 

[Tahmid]

Hi,

If you need microcontrollers with 12-bit ADCs, both Microchip and Atmel have solutions. PIC24F, dsPIC and PIC32 all have 12 bit ADC. Atmel has ATxmega with 12 bit ADC. You can also look at AVR32.

If you are new in micrcontrollers, you shouldn't be doing AVR32, PIC32 or dsPIC. I suggest you use ATxmega or PIC24F if 12 bit ADC is a must or use external ADC.

If you can make do with 10 bit, then use a ATmega or PIC18. For programming you can use BASIC or C. I suggest you take a look at mikroBASIC and mikroC compilers.

Hope this helps.
Tahmid.

 

[bobcat1]

Hi

You can use the STM32f101x4 ARM-cortex M3 micro , it is a power full micro with 12 bit ADC ,low in cost and easy to use (driver library can be directly downloaded from the manufacture site )

All the best

BObi

The microcontroller specialist

 

[amraldo]

Good resources for that STM32 kit is found @ www.micro4you.com
--
Amr Ali

 

[yousafzai82]

Hi all

I used MAX187 as a 12 bit ADC. I interfaced it with PC using the following schematic:



It is working fine and give the exact results. Now i want to interface it with a Microcontroller but i dont know how to interface Dout with a microcontroller.

Added after 2 hours 20 minutes:

Someone Please tell me how to interface Dout, SCLK and CS with a microcontroller....

Added after 1 hours 42 minutes:

Hi can anyone confirm will the interface with MCU work the way given in the figure below:



Added after 2 hours 32 minutes:

Hi wp100 and Tahmid

I need 12 bit resolution because i want to fine the volume of a 2000 liters tank. Now i am changing my plan to PIC18F4550 or ATMEGA8 with FT232BM (USB convertor). My compiler is Hi tech C. I will talk to you after some improvements...

Zahoor Ahmad

 

[bobsanjose]

I need 12 bit resolution because i want to fine the volume of a 2000 liters tank. Now i am changing my plan to PIC18F4550 or ATMEGA8 with FT232BM (USB convertor). My compiler is Hi tech C. I will talk to you after some improvements...

Zahoor Ahmad

You have to help me out with understanding your requirement for the 12 bit. WHat I do understand is that you would like to measure a 2000 L tank to an resolution of 1/2L is that correct.
1. What kind and accuracy is your sensor?
2. Where is it located in the tank?
3. Can you guarantee that the tank is 100% leveled (horizontally)?

If the tank is just some 0.1 degree off and you sensor is not 100% in the center of the tank, you will have more deviation in your measurement from the physical setup than the gain in resolution from 10-bit to 12-bit.

What I am saying is that your setup might be the source of MUCH more inaccuracy than 2 Liter (that would be 1 LSB at 10-bit).

Hope this helps to put things in perspective.
If you really want to use a device with 2x12-bit ADCs, check out the STM32 as Bobi already pointed out. Much easier than your setup.

Cheers, Bob
**broken link removed**

 

[yousafzai82]

Your Question:
You have to help me out with understanding your requirement for the 12 bit. WHat I do understand is that you would like to measure a 2000 L tank to an resolution of 1/2L is that correct.
1. What kind and accuracy is your sensor?
2. Where is it located in the tank?

Ans:
Yes, i am looking for 1/2L accurary.
The Tank is located on a remote site. I have to interface it with a modem then to send the reading through GPRS.

Let me see STM32 as well. Will talk to you after....

 

[JoKKeR]

I bet 18F4553 is good choice for you if you got no budget limits and mass production

is is same as 18f4550 but got 12 bit ADC ... i suppose theres low pin version also.

 

[bejemele]

help, atxmega minimum system schematic?