BH66F2470 Datasheet, PDF (157/223 Pages) Holtek Semiconductor Inc – Glucose Meter Flash MCU

BH66F2470
Glucose Meter Flash MCU
Serial Peripheral Interface – SPIA
The device contains an independent SPI function. It is important not to confuse this independent SPI
function with the additional one contained within the combined SIM function, which is described
in another section of this datasheet. This independent SPI function will carry the name SPIA to
distinguish it from the other one in the SIM.
The SPIA interface is often used to communicate with external peripheral devices such as sensors,
Flash or EEPROM memory devices etc. Originally developed by Motorola, the four line SPIA
interface is a synchronous serial data interface that has a relatively simple communication protocol
simplifying the programming requirements when communicating with external hardware devices.
The communication is full duplex and operates as a slave/master type, where the device can be
either master or slave. Although the SPIA interface specification can control multiple slave devices
from a single master, however the device is provided with only one SCSA pin. If the master needs to
control multiple slave devices from a single master, the master can use I/O pins to select the slave
devices.
SPIA Interface Operation
The SPIA interface is a full duplex synchronous serial data link. It is a four line interface with pin
names SDIA, SDOA, SCKA and SCSA. Pins SDIA and SDOA are the Serial Data Input and Serial
Data Output lines, the SCKA pin is the Serial Clock line and SCSA is the Slave Select line. As the
SPIA interface pins are pin-shared with normal I/O pins, the SPIA interface must first be enabled by
configuring the corresponding selection bits in the pin-shared function selection registers. The SPIA
can be disabled or enabled using the SPIAEN bit in the SPIAC0 register. Communication between
devices connected to the SPIA interface is carried out in a slave/master mode with all data transfer
initiations being implemented by the master. The Master also controls the clock signal. As the device
only contains a single SCSA pin only one slave device can be utilized.
The SCSA pin is controlled by the application program, set the SACSEN bit to "1" to enable the
SCSA pin function and clear the SACSEN bit to "0" to place the SCSA pin into a floating state.
SPIA Master
SCKA
SDOA
SDIA
SCSA
SPIA Slave
SCKA
SDIA
SDOA
SCSA
SPIA Master/Slave Connection
The SPIA function in the device offers the following features:
• Full duplex synchronous data transfer
• Both Master and Slave modes
• LSB first or MSB first data transmission modes
• Transmission complete flag
• Rising or falling active clock edge
The status of the SPIA interface pins is determined by a number of factors such as whether the
device is in the master or slave mode and upon the condition of certain control bits such as SACSEN
and SPIAEN.
Rev. 1.00
157
March 15, 2017