H8SSLASH2225 datasheet(613/1071 Pages) RENESAS

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Section 14 IEBus™ Controller (IEB) [H8S/2258 Group]

Rev. 5.00 Aug 08, 2006 page 527 of 982

REJ09B0054-0500

14.4

Operation Descriptions

14.4.1

Master Transmit Operation

This section describes an example of master transmission using the DTC after slave reception.

(1) IEB Initialization

(a) Setting the IEBus Control Register (IECTR)

Enable the IEBus pins, select the signal polarity, and select a clock supplied to the IEB. Clear

the LUEE bit to 0 since the transfer is performed by the DTC.

(b) Setting the IEBus Master Unit Address Registers 1 and 2 (IEAR1 and IEAR2)

Specify the master unit address and specify the communications mode in IEAR1.

Specify the communications destination slave unit address.

(d) Setting the IEBus Master Control register (IEMCR)

Select broadcast/normal communications, specify the number of retransfer counts at arbitration

loss, and specify the control bits.

(e) Setting the IEBus Transmit Message Length Register (IETBFL)

Specify the message length bits.

(f) Setting the IEBus Transmit/Runaway Interrupt Enable Register (IEIET)

Enable TxRDY (IETxI), TxS, TxF, and TxE (IETSI) interrupts.

The above registers can be specified in any order. (The register specification order does not affect

the IEB operation.)

(2) DTC Initialization

1. Set the start address of the RAM which stores the register information necessary for the DTC

transfer in the vector address (H'000004D4) to be accessed when a DTC transfer request is

generated.

2. Set the following data from the start address of the RAM.

 Transfer source address (SAR): Start address of the RAM which stores data to be

transmitted in the data field.

 Transfer destination address (DAR): Address (H'FFF808) of the IEBus transmit buffer

 Transfer count (CRA): The same value as the IETBFL contents

3. Set DTCEG5 in the DTC enable register G (DTCERG) to enable the TxRDY interrupt

(IETxI).

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