MON51: BAUD RATES
Information in this article applies to:
What baud rates does the MON51 target monitor support?
The MON51 target monitor works at any baud rate. However, depending on the crystal frequency of your target microcontroller, you may be limited in the baud rates that your hardware supports.
For a standard 8051-compatible part at 12.000 MHz, the following table lists the actual baud rates for the indicated timer reload values:
Reload Desired Actual Value Baud Rate Baud Rate Difference FFh 31250 FEh 15625 FDh 9600 10416.66 +8% FCh 9600 7812.5 -22% FBh 6250 FAh 5208.33 F9h 4800 4464.28 -7% F8h 3906.25 F3h 2400 2403.84 +0.1% F2h 2232.14 E6h 1200 1201.92 +0.08% 98h 300 300.48 +0.1%
Different serial devices provide flaxability in supporting non-exact baud rates. However, a good rule of thumb is +1%/-2% for deviations from the baud rate. Therefore, the only baud rates from the above table that are reasonable are 2400, 1200, and 300 baud (for 12MHZ devices).
You should also be aware of slew rates when using a MAX232 or similar driver. The slew rates may also affect the speed you can achieve.
Last Reviewed: Tuesday, January 29, 2002
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