mc9s08jm16 Freescale Semiconductor, Inc, mc9s08jm16 Datasheet - Page 258

• Manufacturer Part Number: mc9s08jm16
• Description: S08jm 8-bit Usb Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

Serial Peripheral Interface (S08SPI16V1)
The baud rate divisor equation is as follows:
The baud rate can be calculated with the following equation:
15.4.7
15.4.7.1
The SS output feature automatically drives the SS pin low during transmission to select external devices
and drives it high during idle to deselect external devices. When SS output is selected, the SS output pin
is connected to the SS input pin of the external device.
The SS output is available only in master mode during normal SPI operation by asserting the SSOE and
MODFEN bits as shown in
The mode fault feature is disabled while SS output is enabled.
15.4.7.2
The bidirectional mode is selected when the SPC0 bit is set in SPI Control Register 2 (see
this mode, the SPI uses only one serial data pin for the interface with external device(s). The MSTR bit
decides which pin to use. The MOSI pin becomes the serial data I/O (MOMI) pin for the master mode, and
the MISO pin becomes serial data I/O (SISO) pin for the slave mode. The MISO pin in master mode and
MOSI pin in slave mode are not used by the SPI.
258
Special Features
SS Output
Bidirectional Mode (MOMI or SISO)
Care must be taken when using the SS output feature in a multi-master
system since the mode fault feature is not available for detecting system
errors between masters.
BUS CLOCK
Table
SPPR2:SPPR1:SPPR0
Figure 15-15. SPI Baud Rate Generation
1, 2, 3, 4, 5, 6, 7, or 8
Baud Rate
BaudRateDivisor
15-2.
MC9S08JM16 Series Data Sheet, Rev. 2
PRESCALER
DIVIDE BY
=
BusClock BaudRateDivisor
NOTE
=
(
⁄
SPPR
2, 4, 8, 16, 32, 64, 128, or 256
+
BAUD RATE DIVIDER
SPR2:SPR1:SPR0
1
) 2
DIVIDE BY
•
(
SPR
+
1
)
Freescale Semiconductor
MASTER
SPI
BIT RATE
Table
15-9.) In