Operation Reservation Commands - Renesas H8S/2158 User Manual

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Section 17 I C Bus Interface (IIC)
17.4.2

Operation Reservation Commands

Table 17.6 lists the operation reservation commands that can be set in ICCMD. If values other
than H'A0 to H'AF, and H'C0 to H'CF are set, H'A0 is automatically set as the command.
The operation reservation commands reserve various operations such as start condition issuance,
stop condition issuance, data transmission (including acknowledge (ACK)/non-acknowledge
(NAK) judgment), and data reception (including ACK/NAK transmission and stop condition
issuance). Since 16 bits can be simultaneously written to ICCMD and ICDRX, a series of required
operations can be written as the transfer data (data + command) for data transmission.
Table 17.7 shows the changes in interrupt flag status and automatic command transition when the
operation reservation command is completed. Each IIC data set consists of the first frame (address
+ read/write) and the subsequent frames (data). Each frame consists of 8-bit data and ACK/NAK;
transmission of ACK or NAK and enabling or disabling NAK judgment must be specified using
the command. The corresponding commands are updated by a command request interrupt (CREQ)
issued after the operation reservation command is completed or automatically updated by the
automatic command transition function. The commands corresponding to the first frame allow
automatic transition. The commands corresponding to the subsequent frames are divided into two
types; some are used for continuous data, which do not allow automatic transition, and others are
used for the last data or a stop condition, which allow automatic transition. A command also
allows automatic transition when arbitration loss occurs.
The commands for continuous data generate a data transfer request interrupt (MRREQ, MTREQ,
SRREQ, or STREQ) after the operation specified by the command is completed (one byte is
processed). To process the last data, update the command at interrupt generation.
Rev. 3.00 Jan 25, 2006 page 512 of 872
REJ09B0286-0300