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7 Segment+Serial RS232

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Dec 28, 2004
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Jakarta, Indonesia
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I'm using ATMEGA8535 for displaying value from ADC into 5 pieces of 5x7 Inch 7 Segment led. I've succedeed in making the MCU works and display the correct value of the voltage with 4 decimal point :)
But unfortunately when I send the value of the ADC to serial port of my pc with speed of 1200 Baud, the 7 segment led got flicked awfully :(
I've try to increase the speed of my serial connection and it works nicely
But why in low speed it doesn't have a nice performance?? Is there anyway to overcome it? I'm using scanning method for my 7 segment led.
Don't suggest me to use shift register, because it's not economical and I've seen the same circuit with the same principal and got works very nice even at low baud rate
I'm looking forward for the answer

You haven't mentioned if you wrote your program using C or ASM or whatever.

IMHO there may be a loop waiting to send the next char via your RS232, and your uC doesn't do anything elese until it is done with sending all four or five characters. During that time your display is not refreshed, so there are long gaps of inactivity in your program, hence the display seems to flicker. Try reordering your code to either use interrupts for each character sent serially, or mix yor xmit routine with display handler routine, so that they don't keep each other waiting.

regards, yego

I'm using BASCOM AVR
It seems your opinion quite right and make sense. It did make waiting routine when I transmit the 5 character. But if I transmitted the char one by one and mix it with the display routine, I hope it will not delay the transmission
I'll try that & I'll send you the result immediately(I'm on the lab right now :D)

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