Rev. 1.10
142
October 23, 2020
Rev. 1.10
143
October 23, 2020
BC66F5652
2.4GHz RF Transceiver A/D Flash MCU
BC66F5652
2.4GHz RF Transceiver A/D Flash MCU
Serial Interface Module – SIM
The device contains a Serial Interface Module, which includes both the four-line SPI interface or
two-line I
2
C interface types, to allow an easy method of communication with external peripheral
hardware. Having relatively simple communication protocols, these serial interface types allow
the microcontroller to interface to external SPI or I
2
C based hardware such as sensors, Flash or
EEPROM memory, etc. The SIM interface pins are pin-shared with other I/O pins and therefore the
SIM interface functional pins must first be selected using the corresponding pin-shared function
selection bits. As both interface types share the same pins and registers, the choice of whether the
SPI or I
2
C type is used is made using the SIM operating mode control bits, named SIM2~SIM0, in
the SIMC0 register. These pull-high resistors of the SIM pin-shared I/O pins are selected using pull-
high control registers if the SIM function is enabled and the corresponding pins are used as SIM
input pins.
SPI Interface
The SPI 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 SPI
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 SPI interface specification can control multiple slave devices
from a single master, the device provides only one SCS pin. If the master needs to control multiple
slave devices from a single master, the master can use I/O pin to select the slave devices.
SPI Interface Operation
The SPI interface is a full duplex synchronous serial data link. It is a four line interface with pin
names SDI, SDO, SCK and SCS. Pins SDI and SDO are the Serial Data Input and Serial Data
Output lines, the SCK pin is the Serial Clock line and SCS is the Slave Select line. As the SPI
interface pins are pin-shared with normal I/O pins and with the I
2
C function pins, the SPI interface
pins must first be selected by setting correct bits in the SIMC0 and SIMC2 registers. After the
desired SPI configuration has been set it can be disabled or enabled using the SIMEN bit in the
SIMC0 register. Communication between devices connected to the SPI 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 SCS pin only one slave device
can be utilized. The SCS pin is controlled by software, set CSEN bit to 1 to enable SCS pin function,
set CSEN bit to 0 the SCS
pin will be floating state.
SCK
SPI Master
SDO
SDI
SCS
SCK
SPI Slave
SDI
SDO
SCS
SPI Master/Slave Connection
The SPI function in this device offers the following features:
• Full duplex synchronous data transfer
• Both Master and Slave modes