III PERIPHERAL BLOCK: SERIAL INTERFACE

Method for setting the serial-interface input/output pins

All of the pins used in the serial interface are shared with I/O ports. At cold start, they are all set for I/O port pins P0x (function select bit Pxx, CFPxx = "0"). When using the serial interface, make function select bit settings for the pins used, according to the channel and transfer mode to be used.

At hot start, the pins retain their status from prior to the reset.

Setting Transfer Mode

The transfer mode of the serial interface can be set using SMDx[1:0] individually for each channel as shown in Table 8.2 below.

Table 8.2 Transfer Mode

SMDx1

SMDx0

Transfer mode

1

1

8-bit asynchronous mode

1

0

7-bit asynchronous mode

0

1

Clock-synchronized slave mode

0

0

Clock-synchronized master mode

Note: SMD11 and SMD31 must be "1" because Ch. 1 and Ch. 3 support only asynchronous operation.

At initial reset, SMDx becomes indeterminate, so be sure to initialize it in the software.

When using the IrDA interface, set the transfer mode for the asynchronous 7-bit or asynchronous 8-bit mode. The input/output pins are configured differently, depending on the transfer mode. The pin configuration in each mode is shown in Table 8.3.

Table 8.3 Pin Configuration by Transfer Mode

Transfer mode

SINx

SOUTx

#SCLKx

#SRDYx

8-bit asynchronous

Data input

Data output

Clock input/P port

P port

7-bit asynchronous

Data input

Data output

Clock input/P port

P port

Clock-synchronized slave

Data input

Data output

Clock input

Ready output

Clock-synchronized

Data input

Data output

Clock output

Ready input

master

 

 

 

 

All four pins are used in the clock-synchronized mode.

In the asynchronous mode, since #SRDYx is unused, P03 (or P23, P24) can be used as an I/O (P) port. In addition, when an external clock is not used, P02 (or P15, P25) can also be used as an I/O port.

The I/O control and data registers for the I/O ports used in the serial interface can be used as general-purpose read/write registers.

Note: To enable the IrDA interface to be set, IRMDx[1:0] (D[1:0]) / Serial I/F IrDA register (Ch.0: 0x401E4, Ch.1: 0x401E9, Ch.2: 0x401F4, Ch.3: 0x401F9) is provided. Since these bits become indeterminate at initial reset, be sure to initialize them by writing "00" when using as the normal interface or "10" when using as the IrDA interface.

S1C33210 FUNCTION PART

EPSON

B-III-8-3