Issues in PIC16F1503

[Aankur]

I am using PIC16F1503 for my automotive application. I want to understand few things:-

1)I have gone through through the schematic present in the "https://ww1.microchip.com/downloads/en/DeviceDoc/50002295A.pdf". In this, PIC 16F1503 is not having external oscillator. I want to know if it is possible to connect external crystal oscillator to PIC16F1503. If yes, which are the pin numbers to which external crystal oscillator can be connected? What is the difference if micro-controller runs on external crystal or on internal oscillator?

2)How to implement UART on PIC16f1503 ? I did not find any RX and TX pin on PIC16F1503.
3)How to implement OTA on PIC16F1503?
4)Is it a good choice for automotive applications?

[jpanhalt]

The external clock pins are CLKIN and CLKOUT.   The pin numbers may depend on which specific chip you have.

The 16F1503 doesn't have hardware USART.  That's pretty easy to do in software, or use another chip in that series that has it.

What is OTA?

[DavidAlfa]

First of all, why that MCU?
Clearly your decision doesn't comply the design requirements.
Price? Check the PIC16F183XX series, the price is very close (Or even cheaper) and have a bunch of peripherals including USART.

The reference design will only give some hints, you need to read the datasheet.
This is a very simple MCU, no special routing is required else than proper grounding and VDD decoupling caps.

By OTA, do you mean upgradable firmware? That's up to you, you need some sort of bootloader that receives and writes a new firmware to the flash.

[jpanhalt]

In my reply, I just went to the datasheet.  As an afterthought, I checked his link.  Apparently, the TS is using a development board (UCS1002) that doesn't have an external crystal.  He has also posted the same question on at least 3 other forums.

My advice:
1) Why do you want an external oscillator?  The internal one is factory calibrated to 1%, and the user can trim it even closer.
2) Review the actual datasheet.
3) As mentioned earlier, if you need hardware USART (called EUSART for enhanced), use a different chip.

EDIT: Here's the pertinent figure from the datasheet (attachment).

[Aankur]

Is PIC16f1503, a good choice for automotive applications?

[jpanhalt]

Is PIC16f1503, a good choice for automotive applications?

Why did you chose it?  And again, why do you want to use a crystal with it?

[woofy]

My advice:
1) Why do you want an external oscillator?  The internal one is factory calibrated to 1%, and the user can trim it even closer.

Please don't take notice of microchip headlines.
Frequency accuracy is +/-2% and that's just at 3v and 25°C. over a 0°C to 60°C range its +/-4.5%. 60°C to 85 its 7%, and outside of that its +/-12% and that's no good at all for a UART,
The OP is correct in needing a crystal, but should choose another device to better match requirements.

[jpanhalt]

Many, many applications work fine with the built-in oscillator.  In fact, the 16F1503 allows a crystal oscillator too.  So the TS's issue with that per se is moot.

Perhaps it would be more contributive if the TS answered specific questions and described what he was trying to do.  Without knowing anything about the project or what he needs, , maybe eve a 10F222 would be a good alternative.  All too often, perhaps almost always, when posters come up with odd requests, the problem is solved by understanding what they want to do.

[hans]

Is PIC16f1503, a good choice for automotive applications?

Depends what it has to do.

If automotive applications means interaction with LIN/CAN buses, then this chip is not a good starting point.

Sure you can always bit-bang an UART to do LIN, but only do it if you're desperate to use this part, for example cost/volume constraints.