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The NXP P89V51RD2 has the ability to choose either Timer1 or Timer2 as the baud rate generator for it's UART.
If I were to use the Timer 1 in mode 2 (auto reload), what is the relation between the baud rate and the crystal frequency in Normal and X2 modes?
I'm using the UART in mode 1(8 bit variable baud rate).
I in Erik's defence suggest you go and look at the manual again.
But if I were to run it in the normal mode, wouldn't the machine cycle be 12 oscillator periods?
Page 1. A key feature of the P89V51RB2/RC2/RD2 is its X2 mode option. The design engineer can choose to run the application with the conventional 80C51 clock rate (12 clocks per machine cycle) or select the X2 mode (six clocks per machine cycle) to achieve twice the throughput at the same clock frequency. Another way to benefit from this feature is to keep the same performance by reducing the clock frequency by half, thus dramatically reducing the EMI.
AS for the baud rate in the rev5 manual in around page 35.
Cheers..
Hello Darren,
I know about the X2 mode.My question was whether the equation will be the same irrespective of the mode.Page 27 says "In the ‘Timer’ function, the register is incremented every machine cycle".Table-58 in page 61 shows that clocks per machine cycle varies with the mode, which is why I had a doubt. All the figures for the timers only show osc/6.
Coming back to my question, the equations mentioned in pages 35-39 are all for timer 2 and _not_ timer 1 :(
Thanks Ravi