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NS9750 - Training Hardware. BBus Utility Block. BBus Utility Overview. Contains global BBus functions including: Master Peripheral Resets BBus DMA Interrupts ARM Wake-up USB Configuration Endian-ness Configuration General Purpose I/O (GPIO). BBus Utility – Master Reset.
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BBus Utility Overview • Contains global BBus functions including: • Master Peripheral Resets • BBus DMA Interrupts • ARM Wake-up • USB Configuration • Endian-ness Configuration • General Purpose I/O (GPIO)
BBus Utility – Master Reset • Master Reset Register contains reset control bits for each BBus peripheral block: • Bbus Utility, BBus DMA, I2C, IEEE 1284, USB and the Serial Controllers (4) • Resets asserted by default after power-on • Reset bits must be de-asserted following power-on reset for each BBus peripheral.
BBus Utility – DMA Interrupts • DMA Interrupt Status/Enable registers include 1-bit for each of the 16 BBus DMA Channels. • Refer to the Users Manual for BBus DMA channel assignments. • DMA Interrupt Status Register should be used to determine which DMA Channel is responsible for setting the BBus Bridge DMA Interrupt Pending status bit .
BBus Utility Configuration • USB Configuration Register contains Speed and Host/Device mode control bits. Refer to the USB documentation in the Users Manual for further information. • Endian-ness Configuration Register controls the Little/Big endian orientation of each of the BBus peripherals and the AHB Master. • Endian-ness of the AHB Master must always match that of the AHB Bus.
BBus Utility – ARM Wake-up • It is possible to Wake-up a sleeping ARM processor by matching pre-defined byte characters on the Serial Controller ‘A’ receive interface. • Should any Rx character byte match a byte in the ARM Wake-Up Register, a wakeup signal will be forwarded from the Bbus to the System Controller Module (SCM).
BBus Utility – GPIOs • 50 General Purpose I/O (GPIO) bits • Each bit can be programmed to select one of the 4 Functions behind that GPIO pin. • For example, GPIO[0] can be allocated to: • Function 0: Ser ChanA TxData _OR_ • Function 1: AHB DMA Chan0 Done _OR_ • Function 2: Timer 1 _OR_ • Function 3: generic GPIO bit<0>
BBus Utility – GPIOs • Each GPIO Configuration Registers (#1 - #7) control 8 GPIO pins, using 4-bits to select direction and function per GPIO pin. • Refer to the NS9750 DataSheet for GPIO Mux function assigments. • For general purpose bits, select Function 3 and specify the pin direction.
BBus Utility – GPIOs • Use GPIO Control Registers to drive the desired value onto the associated output pin. • Use GPIO Status Registers to read the input value from the associated input pin. • Refer to the Users Manual for GPIO bit assignments in the Configuration, Control and Status Registers.
Hints & Kinks • Do all general purpose I/Os (GPIO) have the same drive strength? • No. Most GPIO pins have 2 mA drive strength with the following two exceptions. • LCD Clock requires 8 mA drive strengh • All other LCD outputs require 4 mA drive strength.