Sonic Alert msm83c154s, msm80154s MSM80C154S/83C154S/85C154HVS Mode Outline, Mode 1 baud rate

MSM80C154S/83C154S/85C154HVS

4.6.3.2Mode 1

4.6.3.2.1 Outline

Mode 1 is the 10-bit frame UART mode (with one start bit, eight data bits, and one stop bit) where the baud rate may be set to any value depending on the timer/counter 1 or timer/ counter 2 setting.

A block diagram of the serial port in mode 1 is shown in Figure 4-31, and the operational timing chart is given in Figure 4-32.

4.6.3.2.2 Mode 1 baud rate

The timer/counter 1 or timer/counter 2 overflow can be set as the baud rate clock source in mode 1 by independent TCLK and RCLK setting for the transmit and receive circuits. Where the baud rate is determined by the timer/counter 1 overflow, baud rate is determined by the overflow frequency and SMOD value according to the following equations.

B = fTC1 ⋅	1	⋅	1	(SMOD=0)
	2		16
B = fTC1 ⋅	1			(SMOD=1)
	16

where B is the baud rate and fTC1 is the timer/counter 1 overflow frequency.

When timer/counter 1 is used as a timer (internal clock) in auto reload mode (mode 2), the baud rate is determined by the following equations.

B = fOSC ⋅	1	⋅	1	⋅	1	⋅	1	(SMOD=0)
	12		256-DTH1		2		16
B = fOSC ⋅	1	⋅	1	⋅	1			(SMOD=1)
	12		256-DTH1		16

where B is the baud rate, fOSC the fundamental (XTAL1·2) frequency, and DTH1 the TH1 contents (expressed in decimal).

Where the timer/counter 2 overflow serves as the baud rate clock source, the baud rate is determined by the overflow frequency irrespective of the SMOD value.

When timer/counter 2 is used as a counter (external clock), the baud rate is determined by the following equation.

B = fT2 ⋅	1	⋅	1
	65536-DRCAP2		16

where B is the baud rate, fT2 the frequency of the clock applied to the T2 pin, and DRCAP2 the contents of RCAP2L and RCAP2H (expressed in decimal).

Or if timer/counter 2 is used as a timer, the baud rate is determined in the following way.

110