C8051F902-GM Silicon Laboratories Inc, C8051F902-GM Datasheet - Page 257

• Manufacturer Part Number: C8051F902-GM
• Description: IC MCU 8BIT 8KB FLASH 24QFN
• Manufacturer: Silicon Laboratories Inc
• Series: C8051F9xxr

Specifications of C8051F902-GM

• Program Memory Type: FLASH
• Program Memory Size: 8KB (8K x 8)
• Package / Case: 24-QFN
• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 25MHz
• Connectivity: SMBus (2-Wire/I²C), SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, Temp Sensor, WDT
• Number Of I /o: 16
• Ram Size: 768 x 8
• Voltage - Supply (vcc/vdd): 0.9 V ~ 3.6 V
• Data Converters: A/D 15x10/12b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Processor Series: C8051F9x
• Core: 8051
• Data Ram Size: 768 B
• Interface Type: UART
• Maximum Clock Frequency: 25 MHz
• Number Of Timers: 4
• Operating Supply Voltage: 0.9 V to 3.6 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: PK51, CA51, A51, ULINK2
• Development Tools By Supplier: C8051F912DK
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 12 bit
• Package: 24QFN EP
• Device Core: 8051
• Family Name: C8051F90x
• Maximum Speed: 25 MHz
• Data Bus Width: 8 Bit
• Number Of Programmable I/os: 16
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 336-1848-5

C8051F91x-C8051F90x
24.2. SPI Master Mode Operation
A SPI master device initiates all data transfers on a SPI bus. SPIn is placed in master mode by setting the
Master Enable flag (MSTENn, SPInCN.6). Writing a byte of data to the SPIn data register (SPInDAT) when
in master mode writes to the transmit buffer. If the SPI shift register is empty, the byte in the transmit buffer
is moved to the shift register, and a data transfer begins. The SPIn master immediately shifts out the data
serially on the MOSI line while providing the serial clock on SCK. The SPIFn (SPInCN.7) flag is set to logic
1 at the end of the transfer. If interrupts are enabled, an interrupt request is generated when the SPIF flag
is set. While the SPIn master transfers data to a slave on the MOSI line, the addressed SPI slave device
simultaneously transfers the contents of its shift register to the SPI master on the MISO line in a full-duplex
operation. Therefore, the SPIF flag serves as both a transmit-complete and receive-data-ready flag. The
data byte received from the slave is transferred MSB-first into the master's shift register. When a byte is
fully shifted into the register, it is moved to the receive buffer where it can be read by the processor by
reading SPInDAT.
When configured as a master, SPIn can operate in one of three different modes: multi-master mode, 3-wire
single-master mode, and 4-wire single-master mode. The default, multi-master mode is active when
NSSnMD1 (SPInCN.3) = 0 and NSSnMD0 (SPInCN.2) = 1. In this mode, NSS is an input to the device,
and is used to disable the master SPIn when another master is accessing the bus. When NSS is pulled low
in this mode, MSTENn (SPInCN.6) and SPIENn (SPInCN.0) are set to 0 to disable the SPI master device,
and a Mode Fault is generated (MODFn, SPInCN.5 = 1). Mode Fault will generate an interrupt if enabled.
SPIn must be manually re-enabled in software under these circumstances. In multi-master systems,
devices will typically default to being slave devices while they are not acting as the system master device.
In multi-master mode, slave devices can be addressed individually (if needed) using general-purpose I/O
pins. Figure 24.2 shows a connection diagram between two master devices in multiple-master mode.
3-wire single-master mode is active when NSSnMD1 (SPInCN.3) = 0 and NSSnMD0 (SPInCN.2) = 0. In
this mode, NSS is not used, and is not mapped to an external port pin through the crossbar. Any slave
devices that must be addressed in this mode should be selected using general-purpose I/O pins.
Figure 24.3 shows a connection diagram between a master device in 3-wire master mode and a slave
device.
4-wire single-master mode is active when NSSnMD1 (SPInCN.3) = 1. In this mode, NSS is configured as
an output pin, and can be used as a slave-select signal for a single SPI device. In this mode, the output
value of NSS is controlled (in software) with the bit NSSnMD0 (SPInCN.2). Additional slave devices can be
addressed using general-purpose I/O pins. Figure 24.4 shows a connection diagram for a master device in
4-wire master mode and two slave devices.
Rev. 1.0
257