MC9S08JM16 Datasheet, PDF (246/386 Pages) Freescale Semiconductor, Inc – Microcontrollers

Serial Peripheral Interface (S08SPI16V1)
Field
7
SPIE
6
SPE
5
SPTIE
4
MSTR
3
CPOL
2
CPHA
1
SSOE
0
LSBFE
Table 15-1. SPIxC1 Field Descriptions
Description
SPI Interrupt Enable (for SPRF and MODF) — This is the interrupt enable for SPI receive buffer full (SPRF)
and mode fault (MODF) events.
0 Interrupts from SPRF and MODF inhibited (use polling)
1 When SPRF or MODF is 1, request a hardware interrupt
SPI System Enable — This bit enables the SPI system and dedicates the SPI port pins to SPI system functions.
If SPE is cleared, SPI is disabled and forced into idle state, and all status bits in the SPIxS register are reset.
0 SPI system inactive
1 SPI system enabled
SPI Transmit Interrupt Enable — This is the interrupt enable bit for SPI transmit buffer empty (SPTEF).
0 Interrupts from SPTEF inhibited (use polling)
1 When SPTEF is 1, hardware interrupt requested
Master/Slave Mode Select — This bit selects master or slave mode operation.
0 SPI module configured as a slave SPI device
1 SPI module configured as a master SPI device
Clock Polarity — This bit selects an inverted or non-inverted SPI clock. To transmit data between SPI modules,
the SPI modules must have identical CPOL values.
This bit effectively places an inverter in series with the clock signal from a master SPI or to a slave SPI device.
Refer to Section 15.4.5, “SPI Clock Formats” for more details.
0 Active-high SPI clock (idles low)
1 Active-low SPI clock (idles high)
Clock Phase — This bit selects one of two clock formats for different kinds of synchronous serial peripheral
devices. Refer to Section 15.4.5, “SPI Clock Formats” for more details.
0 First edge on SPSCK occurs at the middle of the first cycle of a data transfer
1 First edge on SPSCK occurs at the start of the first cycle of a data transfer
Slave Select Output Enable — This bit is used in combination with the mode fault enable (MODFEN) bit in
SPIxC2 and the master/slave (MSTR) control bit to determine the function of the SS pin as shown in Table 15-2.
LSB First (Shifter Direction) — This bit does not affect the position of the MSB and LSB in the data register.
Reads and writes of the data register always have the MSB in bit 7 (or bit 15 in 16-bit mode).
0 SPI serial data transfers start with most significant bit
1 SPI serial data transfers start with least significant bit
MODFEN
0
0
1
1
SSOE
0
1
0
1
Table 15-2. SS Pin Function
Master Mode
General-purpose I/O (not SPI)
General-purpose I/O (not SPI)
SS input for mode fault
Automatic SS output
Slave Mode
Slave select input
Slave select input
Slave select input
Slave select input
15.3.2 SPI Control Register 2 (SPIxC2)
This read/write register is used to control optional features of the SPI system. Bits 6 and 5 are not
implemented and always read 0.
MC9S08JM16 Series Data Sheet, Rev. 2
246
Freescale Semiconductor