M38005M2DXXXFP View Datasheet(PDF) - MITSUBISHI ELECTRIC

Part Name

Description

Manufacturer

M38005M2DXXXFP

8-BIT SINGLE-CHIP MICROCOMPUTER

MITSUBISHI ELECTRIC  

APPLICATION

2.3 Serial I/O

Control in the slave unit

After a setting of the related registers is completed as shown in Figure 2.3.26, the slave unit becomes the

state which is received a synchronizing clock at all times, and the Serial I/O receive interrupt request bit is

set to “1” every time an 8-bit synchronous clock is received.

By the serial I/O receive interrupt processing routine, the data to be transmitted next is written to the Transmit

buffer register after received data is read out.

However, if no serial I/O receive interrupt occurs for more than a certain time (head adjustive time), the

following processing will be performed.

1. The first 1 byte data of the transmission data in the block is written into the Transmit buffer register.

2. The data to be received next is processed as the first 1 byte of the received data in the block.

Figure 2.3.28 shows the control in the slave unit using a serial I/O receive interrupt and any timer interrupt

(for head adjustive).

Serial I/O receive interrupt

processing routine

Timer interrupt processing

routine

CLT (Note 1)

CLD (Note 2)

Push register to stack

q Push the register used in

the interrupt processing

routine into the stack.

q Check the received byte

counter to judge if a block

N has been transfered.

Within a block transfer period?

Y

Read a reception data

A received byte counter +1

CLT (Note 1)

CLD (Note 2)

Push register to stack

q Push the register used in

the interrupt processing

routine into the stack.

Heading adjustive counter – 1

Heading adjustive

N

counter = 0?

Y

Write the first transmission data

(first byte) in a block

Y

A received byte counter ≥ 8?

N

Write a transmission data

Write any data (FF16)

Heading adjustive Initialized

counter

value (Note 3)

A received byte counter 0

Pop registers

RTI

q Pop registers which is

pushed to stack.

Pop registers

q Pop registers which is

pushed to stack.

RTI

Fig. 2.3.28 Control in the slave unit

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

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

3: In this example, set the value which is equal to the

heading adjustive time divided by the timer interrupt

cycle as the initialized value of the heading adjustive

counter.

For example: When the heading adjustive time is 8 ms

and the timer interrupt cycle is 1 ms, set

8 as the initialized value.

2-42

3800 GROUP USER’S MANUAL

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