View Full Version : Help on Oscillators

07-26-2005, 10:59 PM
Hey can anyone help me finding when to use an oscillator with a uC and when to not? How to select the oscillator and the capacitors required ? How many types of oscialltors are available in the market ?

07-27-2005, 11:36 PM
You will always need to have an oscillator (excitement) to run a Uc..
There are many ways to do it...some micros have inbuilt Resistor-capacitor oscillators,some need external crystals,some a simple r/c network.

If your connecting the oscilllator externally like it's mostly done,you will need a crystal and 2 caps..check your Uc's datasheet for capacitor values.

Which Uc are you using?

07-28-2005, 01:13 AM
Well I am using AT89S52 and AT89C2051, I want to program them with a hand made programmer that also with minimum fuss, thats why I have opted for BlowIT programmer for 2051 and AEC Electronics programmer for S52. Tell me what frequency of the oscillator will be the best suited one for these uCs. I have used 10MHz with 33pF capacitors for S52 but it didnt get programmed. I am using the AEC software to program it but it is giving errors saying "Error writing FLash!". Suggest me some remedy.......

07-29-2005, 05:28 PM
Try using a 12MHz Crystal coz maybe your baud rate is not matching ... Also 12MHz or a 11.XX MHz is better if you want to use serial communication. I have used a 12MHz crystal with a AT89C2051 and AT89S8252, without any problems...

Hope that helps

Nimesh S Chinoy