C8051F526-IMR Silicon Labs, C8051F526-IMR Datasheet - Page 155

• Manufacturer Part Number: C8051F526-IMR
• Description: 8-bit Microcontrollers - MCU 2KB 12ADC 125C LIN 10Pin MCU
• Manufacturer: Silicon Labs

Specifications of C8051F526-IMR

• Product Category: 8-bit Microcontrollers - MCU
• Rohs: yes
• Core: 8051
• Data Bus Width: 8 bit
• Maximum Clock Frequency: 25 MHz
• Program Memory Size: 2 KB
• Data Ram Size: 256 B
• On-chip Adc: Yes
• Package / Case: DFN-10
• Mounting Style: SMD/SMT
• A/d Bit Size: 12 bit
• A/d Channels Available: 6
• Interface Type: SPI, UART
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 40 C
• Number Of Programmable I/os: 6
• Number Of Timers: 3
• On-chip Dac: No
• Processor Series: C8051
• Program Memory Type: Flash
• Factory Pack Quantity: 1500
• Supply Voltage - Max: 2.7 V, 5.25 V
• Supply Voltage - Min: 2 V, 2.7 V

The shift register contents are locked after the slave detects the first edge of SCK. Writes to SPI0DAT that
occur after the first SCK edge will be held in the TX latch until the end of the current transfer.
When configured as a slave, SPI0 can be configured for 4-wire or 3-wire operation. The default, 4-wire
slave mode, is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 1. In 4-wire mode, the
NSS signal is routed to a port pin and configured as a digital input. SPI0 is enabled when NSS is logic 0,
and disabled when NSS is logic 1. The bit counter is reset on a falling edge of NSS. Note that the NSS sig-
nal must be driven low at least 2 system clocks before the first active edge of SCK for each byte transfer.
Figure 16.4 shows a connection diagram between two slave devices in 4-wire slave mode and a master
device.
3-wire slave mode is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 0. NSS is not
used in this mode, and is not mapped to an external port pin through the crossbar. Since there is not a way
of uniquely addressing the device in 3-wire slave mode, SPI0 must be the only slave device present on the
bus. It is important to note that in 3-wire slave mode there is no external means of resetting the bit counter
that determines when a full byte has been received. The bit counter can only be reset by disabling and re-
enabling SPI0 with the SPIEN bit. Figure 16.3 shows a connection diagram between a slave device in 3-
wire slave mode and a master device.
16.4. SPI0 Interrupt Sources
When SPI0 interrupts are enabled, the following four flags will generate an interrupt when they are set to
logic 1:
Note that all of the following interrupt bits must be cleared by software.
1. The SPI Interrupt Flag, SPIF (SPI0CN.7) is set to logic 1 at the end of each byte transfer. This flag can
2. The Write Collision Flag, WCOL (SPI0CN.6) is set to logic 1 if a write to SPI0DAT is attempted when
3. The Mode Fault Flag MODF (SPI0CN.5) is set to logic 1 when SPI0 is configured as a master in multi-
4. The Receive Overrun Flag RXOVRN (SPI0CN.4) is set to logic 1 when configured as a slave, and a
occur in all SPI0 modes.
the transmit buffer has not been emptied to the SPI shift register. When this occurs, the write to
SPI0DAT will be ignored, and the transmit buffer will not be written.This flag can occur in all SPI0
modes.
master mode and the NSS pin is pulled low. When a Mode Fault occurs, the MSTEN and SPIEN bits in
SPI0CN are set to logic 0 to disable SPI0 and allow another master device to access the bus.
transfer is completed while the receive buffer still holds an unread byte from a previous transfer. The
new byte is not transferred to the receive buffer, allowing the previously received data byte to be read.
The data byte which caused the overrun is lost.
Rev. 1.4
C8051F52x/F53x
155