C8051F313R Silicon Labs, C8051F313R Datasheet - Page 174

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C8051F313R

Manufacturer Part Number
C8051F313R
Description
8-bit Microcontrollers - MCU 8KB 10ADC
Manufacturer
Silicon Labs
Datasheet

Specifications of C8051F313R

Product Category
8-bit Microcontrollers - MCU
Core
8051
Data Bus Width
8 bit
Maximum Clock Frequency
25 MHz
Program Memory Size
8 KB
Data Ram Size
1.25 KB
On-chip Adc
Yes
Operating Supply Voltage
2.7 V to 3.6 V
Package / Case
QFN-28
Mounting Style
SMD/SMT
A/d Bit Size
10 bit
A/d Channels Available
17
Data Rom Size
128 B
Interface Type
I2C, SMBus, SPI, UART
Maximum Operating Temperature
+ 85 C
Minimum Operating Temperature
- 40 C
Number Of Programmable I/os
25
Number Of Timers
5
On-chip Dac
No
Processor Series
C8051
Program Memory Type
Flash
Factory Pack Quantity
1500
Supply Voltage - Max
3.6 V
Supply Voltage - Min
2.7 V
C8051F310/1/2/3/4/5/6/7
16.1. Signal Descriptions
The four signals used by SPI0 (MOSI, MISO, SCK, NSS) are described below.
16.1.1. Master Out, Slave In (MOSI)
The master-out, slave-in (MOSI) signal is an output from a master device and an input to slave devices. It
is used to serially transfer data from the master to the slave. This signal is an output when SPI0 is operat-
ing as a master and an input when SPI0 is operating as a slave. Data is transferred most-significant bit
first. When configured as a master, MOSI is driven by the MSB of the shift register in both 3- and 4-wire
mode.
16.1.2. Master In, Slave Out (MISO)
The master-in, slave-out (MISO) signal is an output from a slave device and an input to the master device.
It is used to serially transfer data from the slave to the master. This signal is an input when SPI0 is operat-
ing as a master and an output when SPI0 is operating as a slave. Data is transferred most-significant bit
first. The MISO pin is placed in a high-impedance state when the SPI module is disabled and when the SPI
operates in 4-wire mode as a slave that is not selected. When acting as a slave in 3-wire mode, MISO is
always driven by the MSB of the shift register.
16.1.3. Serial Clock (SCK)
The serial clock (SCK) signal is an output from the master device and an input to slave devices. It is used
to synchronize the transfer of data between the master and slave on the MOSI and MISO lines. SPI0 gen-
erates this signal when operating as a master. The SCK signal is ignored by a SPI slave when the slave is
not selected (NSS = 1) in 4-wire slave mode.
16.1.4. Slave Select (NSS)
The function of the slave-select (NSS) signal is dependent on the setting of the NSSMD1 and NSSMD0
bits in the SPI0CN register. There are three possible modes that can be selected with these bits:
See Figure 16.2, Figure 16.3, and Figure 16.4 for typical connection diagrams of the various operational
modes. Note that the setting of NSSMD bits affects the pinout of the device. When in 3-wire master or
3-wire slave mode, the NSS pin will not be mapped by the crossbar. In all other modes, the NSS signal will
be mapped to a pin on the device. See Section
port I/O and crossbar information.
174
NSSMD[1:0] = 00: 3-Wire Master or 3-Wire Slave Mode: SPI0 operates in 3-wire mode, and NSS is
disabled. When operating as a slave device, SPI0 is always selected in 3-wire mode. Since no select
signal is present, SPI0 must be the only slave on the bus in 3-wire mode. This is intended for point-to-
point communication between a master and one slave.
NSSMD[1:0] = 01: 4-Wire Slave or Multi-Master Mode: SPI0 operates in 4-wire mode, and NSS is
enabled as an input. When operating as a slave, NSS selects the SPI0 device. When operating as a
master, a 1-to-0 transition of the NSS signal disables the master function of SPI0 so that multiple mas-
ter devices can be used on the same SPI bus.
NSSMD[1:0] = 1x: 4-Wire Master Mode: SPI0 operates in 4-wire mode, and NSS is enabled as an out-
put. The setting of NSSMD0 determines what logic level the NSS pin will output. This configuration
should only be used when operating SPI0 as a master device.
“13. Port
Rev. 1.7
Input/Output” on page
129
for general purpose

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