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1745D–ATARM–04-Nov-05
AT91M55800A
• PCS: Peripheral Chip Select (Code Label SP_PCS)
This field is only used if Fixed Peripheral Select is active (PS=0).
If PCSDEC=0:
PCS = xxx0NPCS[3:0] = 1110 (Code Label SP_PCS0)
PCS = xx01NPCS[3:0] = 1101 (Code Label SP_PCS1)
PCS = x011NPCS[3:0] = 1011 (Code Label SP_PCS2)
PCS = 0111NPCS[3:0] = 0111 (Code Label SP_PCS3)
PCS = 1111forbidden (no peripheral is selected)
(x = don’t care)
If PCSDEC=1:
NPCS[3:0] output signals = PCS.
• DLYBCS: Delay Between Chip Selects (Code Label SP_DLYBCS)
This field defines the delay from NPCS inactive to the activation of another NPCS. The DLYBCS time guarantees non-over-
lapping chip selects and solves bus contentions in case of peripherals having long data float times.
If DLYBCS is less than or equal to six, six SPI Master Clock periods will be inserted by default.
Otherwise, the following equation determines the delay:
Delay_ Between_Chip_Selects = DLYBCS * SPI_Master_Clock_period