Digi NS9215 manual A c o n t r o l l e r, AHB slave, Interface, Servicing RX and FIFOs

Models: NS9215

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I / O H U B M O D U L E

DMA controller

Block diagram

AMBA AHB Bus

to SCM Interrupt

Controller

AHB Master

AHB Slave

DMA Controller

 

Rsvd

Rsvd

 

UART A

 

UART B

 

UART C UART D

 

A/D

 

SPI

 

I2C

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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AHB slave

The CPU has access to the control and status registers in the DMA controller, the

interface

peripheral devices, and the GPIO configuration.

D M A c o n t r o l l e r

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Servicing RX and FIFOs

The processor provides an eight channel DMA controller to service the low speed peripherals. Each channel has a transmit channel and a receive channel.

The DMA controller services the RX and FIFOs in a round-robin manner. When one of the FIFOs needs servicing — that is, it can accept a burst of four 32-bit words — the DMA controller requests the AHB bus through the AHB master. After the request has been granted, the peripheral buffer data is transferred to or from system memory.

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Hardware Reference NS9215

31 March 2008

Page 364
Image 364
Digi NS9215 manual A c o n t r o l l e r, AHB slave, Interface, Servicing RX and FIFOs