Panasonic MN103001G/F01K - Manual (Page 316)

Serial Interface
13-14
SBO
SBI
SBT
SBO
SBI
SBT
SBO
SBI
SBO
SBI
SBT SBT
Reception Transmission
Transmission/
reception
Transmission/
reception
External
clock
External
clock
Bi-directional transfer Undirectional transfer
<UART mode>
■ UART mode connection
Two different connection methods are possible, one for unidirectional transfer, and the other for bi-directional
transfer.
The SBO pin is always an output, and the SBI pin is always an input.
Fig. 13-2-8 Connections
■ UART mode bit rates
In UART mode, it is necessary to select an appropriate bit rate and serial interface input clock.
For example, when IOCLK = 15 MHz and the bit rate is 19.2 kbit/s, the timer function is used to divide the clock
signal. The division ratio is determined as follows:
Timer division ratio = INT (IOCLK frequency/bit rate/8 + 0.5)
In the example described above, the timer division ratio is 98.
In the timer 3 base register, set TM3BR = 97 and set SC0CK2 to 0 = "100". IOCLK divided by 98 will then be
supplied to the serial interface as the input clock. The bit rate error is calculated as follows:
Bit rate error = ABS (division ratio x 8 x bit rate/IOCLK frequency - 1)
In this example, the bit rate error is 0.35 %.
Typical examples are shown in Tables 13-2-2 through 13-2-4.
Note: When 1/8 of an external clock signal is used as the clock source, the high and low widths of the external
clock must be at least 10, 5, or 2.5 SYSCLK cycles when (MCLK frequency/SYSCLK frequency) = 1, 2, or
4, respectively.
If the division ratio is large, use either a prescaler or a cascaded connection for the timer.