UPD784026 Renesas Electronics Corporation., UPD784026 Datasheet - Page 488

• Manufacturer Part Number: UPD784026
• Description: 16/8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

17.5.1 SBI Features
between the chip select signal and commands/data, to identify the busy state, etc., when the serial bus is configured with
a number of devices connected. Moreover, if the associated control is performed by software, this represents a considerable
burden for software.
of SBI leads to reduction in the number of microcontroller ports and that of wirings and routings on the board.
(1) Address/command/data differentiation function
(2) Chip selection by address
(3) Wake-up function
(4) Acknowledge signal (ACK) control function
(5) Busy signal (BUSY) control function
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Since conventional serial I/O methods only have data transfer functions, many ports and wires are required to distinguish
In SBI, a serial bus can be configured with two signal lines of serial clock SCK0 and serial data bus SB0. Thus, use
SBI functions are described below.
Identifies serial data as an address, command or actual data.
The master performs slave chip selection by address transmission.
A slave can identify address reception (chip selection) easily by means of the wake-up function (settable/ releasable
in software).
When the wake-up function is set, a serial reception interrupt (INTCSI) is generated only when an address is received.
As a result, non-selected CPUs can operate without regard to serial communications even when communication with
multiple devices is performed.
Controls the acknowledge signal used to confirm serial data reception.
Controls the busy signal used to give notification of a slave busy status.
CHAPTER 17 CLOCKED SERIAL INTERFACE