at91sam9260-cj ATMEL Corporation, at91sam9260-cj Datasheet - Page 369

• Manufacturer Part Number: at91sam9260-cj
• Description: At91 Arm Thumb Microcontrollers
• Manufacturer: ATMEL Corporation

Figure 30-8. Peripheral Deselection
30.6.3.8
30.6.4
6221G–ATARM–31-Jan-08
Write SPI_TDR
Write SPI_TDR
Write SPI_TDR
NPCS[0..3]
NPCS[0..3]
NPCS[0..3]
TDRE
TDRE
TDRE
SPI Slave Mode
Mode Fault Detection
A
A
A
DLYBCT
DLYBCT
DLYBCT
Figure 30-8
A mode fault is detected when the SPI is programmed in Master Mode and a low level is driven
by an external master on the NPCS0/NSS signal. NPCS0, MOSI, MISO and SPCK must be con-
figured in open drain through the PIO controller, so that external pull up resistors are needed to
guarantee high level.
When a mode fault is detected, the MODF bit in the SPI_SR is set until the SPI_SR is read and
the SPI is automatically disabled until re-enabled by writing the SPIEN bit in the SPI_CR (Con-
trol Register) at 1.
By default, the Mode Fault detection circuitry is enabled. The user can disable Mode Fault
detection by setting the MODFDIS bit in the SPI Mode Register (SPI_MR).
When operating in Slave Mode, the SPI processes data bits on the clock provided on the SPI
clock pin (SPCK).
The SPI waits for NSS to go active before receiving the serial clock from an external master.
When NSS falls, the clock is validated on the serializer, which processes the number of bits
CSAAT = 0
DLYBCS
DLYBCS
DLYBCS
PCS = B
shows different peripheral deselection cases and the effect of the CSAAT bit.
PCS=A
PCS = A
A
B
A
A
A
A
DLYBCT
DLYBCT
DLYBCT
CSAAT = 1
DLYBCS
DLYBCS
PCS = B
PCS = A
A
A
AT91SAM9260
PCS = A
DLYBCS
A
A
B
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