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ST72324 Fiches technique(PDF) 88 Page - STMicroelectronics |
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ST72324 Fiches technique(HTML) 88 Page - STMicroelectronics |
88 / 163 page ST72324 88/163 SERIAL PERIPHERAL INTERFACE (Cont’d) CONTROL/STATUS REGISTER (SPICSR) Read/Write (some bits Read Only) Reset Value: 0000 0000 (00h) Bit 7 = SPIF Serial Peripheral Data Transfer Flag (Read only). This bit is set by hardware when a transfer has been completed. An interrupt is generated if SPIE=1 in the SPICR register. It is cleared by a software sequence (an access to the SPICSR register followed by a write or a read to the SPIDR register). 0: Data transfer is in progress or the flag has been cleared. 1: Data transfer between the device and an exter- nal device has been completed. Note: While the SPIF bit is set, all writes to the SPIDR register are inhibited until the SPICSR reg- ister is read. Bit 6 = WCOL Write Collision status (Read only). This bit is set by hardware when a write to the SPIDR register is done during a transmit se- quence. It is cleared by a software sequence (see Figure 51). 0: No write collision occurred 1: A write collision has been detected Bit 5 = OVR SPI Overrun error (Read only). This bit is set by hardware when the byte currently being received in the shift register is ready to be transferred into the SPIDR register while SPIF = 1 (See Section 10.4.5.2). An interrupt is generated if SPIE = 1 in SPICR register. The OVR bit is cleared by software reading the SPICSR register. 0: No overrun error 1: Overrun error detected Bit 4 = MODF Mode Fault flag (Read only). This bit is set by hardware when the SS pin is pulled low in master mode (see Section 10.4.5.1 Master Mode Fault (MODF)). An SPI interrupt can be generated if SPIE=1 in the SPICSR register. This bit is cleared by a software sequence (An ac- cess to the SPICR register while MODF=1 fol- lowed by a write to the SPICR register). 0: No master mode fault detected 1: A fault in master mode has been detected Bit 3 = Reserved, must be kept cleared. Bit 2 = SOD SPI Output Disable. This bit is set and cleared by software. When set, it disables the alternate function of the SPI output (MOSI in master mode / MISO in slave mode) 0: SPI output enabled (if SPE=1) 1: SPI output disabled Bit 1 = SSM SS Management. This bit is set and cleared by software. When set, it disables the alternate function of the SPI SS pin and uses the SSI bit value instead. See Section 10.4.3.2 Slave Select Management. 0: Hardware management (SS managed by exter- nal pin) 1: Software management (internal SS signal con- trolled by SSI bit. External SS pin free for gener- al-purpose I/O) Bit 0 = SSI SS Internal Mode. This bit is set and cleared by software. It acts as a ‘chip select’ by controlling the level of the SS slave select signal when the SSM bit is set. 0: Slave selected 1: Slave deselected DATA I/O REGISTER (SPIDR) Read/Write Reset Value: Undefined The SPIDR register is used to transmit and receive data on the serial bus. In a master device, a write to this register will initiate transmission/reception of another byte. Notes: During the last clock cycle the SPIF bit is set, a copy of the received data byte in the shift register is moved to a buffer. When the user reads the serial peripheral data I/O register, the buffer is actually being read. While the SPIF bit is set, all writes to the SPIDR register are inhibited until the SPICSR register is read. Warning: A write to the SPIDR register places data directly into the shift register for transmission. A read to the SPIDR register returns the value lo- cated in the buffer and not the content of the shift register (see Figure 46). 70 SPIF WCOL OVR MODF - SOD SSM SSI 70 D7 D6 D5 D4 D3 D2 D1 D0 1 |
Numéro de pièce similaire - ST72324_05 |
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Description similaire - ST72324_05 |
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