Cheapest Microcontroller with I2C & UART for industrial use?

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Joined Aug 23, 2009

I'm designing a 3.3V microcontroller based project that need to interact with two chips using UART and I2C. I would like to ask everyone what is the cheapest/smallest microcontroller to use? We plan to make tens of thousands of boards with the chosen microcontroller so I want to ask professional opinion before we decide what to use.

Basically the Microcontroller has to read data from the first chip using UART(3.3V, 19200bps), then write it to the second chip using I2C; The microcontroller then read the processed data from the second chip via I2C and write it to the first chip via UART. The microcontroller need to be the I2C master.

I see there are many 8-bit PIC microcontrollers from Microchip that have hardware based I2C & UART modules. But I heard PICs are not really used in a industrial setting and are used mostly by hobbyists.

I'd be really grateful if anyone can share suggestions on where do I start to decide the best microcontroller to use? it needs to be as small as possible, and due to the large number of PCB boards we will make, price is also a big concern.

Thanks in advance!!!



Joined Jan 8, 2009
You have a number of options of which I would say AT90S2313, PIC's or the PICAXE
You didnt specify the number of ports though which has a major role in selecting the uC.
At90S2313 is cheap has Full Duplex UART but havent checked of it has I2C and has 15 ports. PIC AT90S2323 is smaller but havent checked abt it. In PIC you have lots of options

PIC's are used for industrial purposes. I have a ups having a PIC 16F and works reliabily. check datasheets for size, ports, voltage and UART and I2C


Joined Nov 6, 2005
Whoever said PICs are not used for industrial gear is talking rhubarb...

The development tools are excellent and free (MPLab) or very cheap (hardware & C compilers etc).

I'd definitely go with an appropriate PIC.


Joined Apr 18, 2009
i really doubt microchip would be producing PICs in current quantities if they werent meant for commercial and industrial use. I highly doubt they would be worth producing at all if only for hobbyists;)


Joined Oct 14, 2005
If you are really planning to make tens of thousands of them, then you are better off contacting and asking the manufacturers directly. There are many to choose from, Microchip, Atmel, TI, etc. They will point you to the most suitable device and give you better offer (price, stock, schedule, etc.). And some will even help you in design :)
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Joined Jun 7, 2009
I doubt anyone of us here is privey to pricing at those volumes. All the manufacturers will custom price, assign engineers to your needs, and produce dies specifically for your needs, at those volumes. But before they do that, they'll want to see how valid your claims are.


Joined May 7, 2007
Take a look at the SC18IM700 from NXP[pip=SC18IM700_2]|pp=[t=pip,i=SC18IM700_2]

From Atmel there are the ATtiny2313 and ATmega48 devices that would get you under a dollar at those quantities. I do not have current pricing for PIC16F687/690s but they are also less than a buck at higher quantities.

If you had higher quantities then you can talk ASIC. Tens of thousands wont get you a custom die but it might get a custom package. For the application you described the NXP part sounds like the best fit-- if all you are doing is a uart-I2C conversion.

Now when you say cheapest/smallest -- how cheap and how small?

The mega48 and tiny2313 come in a 4mmX4mm package.
I think the PIC16F687/690 also come in a 4x4 mm pkg.
There are some 3x3 mm parts out there but I think they do not have both uart and i2c.

There are a lot of commercial products with PICs but they do not have the largest share (yet). But among hobbyists and beginners they have a strong presence and so they are expanding and getting design wins into more commercial products. Atmel's AVR is also growing and they are also very hobbyist and beginner friendly. They are easier to migrate among devices since their core is the same among all their devices. With PIC you have to watch out for this.

Since this is a commercial product then you also need to look at software licensing. If you buy compiler software then you have no problem but if you use the LITE or student or free versions then you need to check it out. This applies mostly to PIC. The AVR has a full open source compiler that is free (and not crippled) called WinAVR. AVR also has other compiler vendors that are not free -- codevision, imagecraft, iar, and others. PIC has Microchip/Hi-Tech, CCS, MikroC and others.

Both PICs and AVRs can be purchased pre-programmed.

Anyway I am rambling...
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Joined May 30, 2008
PICs are not a bad choice. I've seen lots of devices carrying PICs in them and I've been using them and have proven themselves reliable. I'd use the PIC24 in your case. It's got UART and I2C. There are different packages to choose from and each has a specific number of ports.

I'm currently working on a project with the PIC24HJ12GP202 This is a 28 pin uC (it's got UART and I2C).