M38B53M4-059FP datasheet(158/355 Pages) MITSUBISHI

158 / 355 page

2-70

38B5 Group User’s Manual

APPLICATION

2.3 Serial I/O

Control procedure by software:

q Control in the master unit

After setting the relevant registers shown in Figure 2.3.46, the master unit starts transmission or

reception of 1-byte data by writing transmission data to the serial I/O2 transmit buffer register.

To perform the communication in the timing shown in Figure 2.3.45, take the timing into account

and write transmission data. Additionally, read out the reception data when the serial I/O2 transmit

interrupt request bit is set to “1,” or before the next transmission data is written to the serial I/O2

transmit buffer register.

Figure 2.3.48 shows a control procedure of the master unit using timer interrupts.

Interrupt processing routine

executed every 500

µs

Write a transmission data

Read a reception data

Within a block transfer

period?

Complete to transfer

a block?

RTI

Write the first transmission data

(first byte) in a block

Count a block interval counter

Start a block transfer?

Generating a certain block interval by

using a timer or other functions

Check of the block interval counter and

determination to start a block transfer

CLT (Note 1)

CLD (Note 2)

Push register to stack

Note 1: When using the Index X mode flag (T).

Note 2: When using the Decimal mode flag (D).

Pushing the register used in the interrupt

processing routine into the stack

Pop registers

Popping registers which is pushed to stack

Fig. 2.3.48 Control procedure of master unit

M38B53M4-059FP Datasheet(PDF) 158 Page - Mitsubishi Electric Semiconductor