
. . . . .
I / O H U B M O D U L E
Transmit DMA example
www.digiembedded.com
367
HDLC
SPI
Not applicable.
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T r a n s m i t D M A e x a m p l e
After the last buffer in the data packet has been placed in system memory and the
buffer descriptors have been configured, the data packet is ready to be transmitted.
The CPU configures the module DMA TX buffer descriptor pointer, TXBDP (see
“[Module] DMA TX Buffer Descriptor Pointer” on page 381), and then sets the channel
enable bit in the DMA Control register.
Process
The DMA controller starts the process to read the buffer descriptor and buffer data
from system memory using the AHB master. The DMA controller follows this process:
1
Reads the first buffer descriptor, as pointed to by the TX buffer descriptor
pointer and INDEX.
Bits
Description
15:7
Reserved
6:5
01
HDLC frame close, bits 3:0 indicate the close condition
bit 4: The last byte is less than 8 bits
bit 3: Receiver overflow, should never occur in a properly configured system
bit 2: Invalid CRC found at end of frame
bit 1: Valid CRC found at end of frame
bit 0: Abort condition found
11
match character found
bit 4: Match character 4
bit 3: Match character 3
bit 2: Match character 2
bit 1: Match character 1
bit 0: Match character 0
00
Other close event
bit 2: Buffer gap timer expired
bit 1: Software-initiated buffer close
Summary of Contents for NS9215
Page 1: ...NS9215 Hardware Reference 90000847_C Release date 10 April 2008...
Page 3: ......
Page 4: ......
Page 26: ...26 Hardware Reference NS9215...
Page 44: ...P I N O U T 26 5 System clock 44 Hardware Reference NS9215 System clock drawing...
Page 52: ...P I N O U T 26 5 Power and ground 52 Hardware Reference NS9215...
Page 80: ...I O C O N T ROL M O D U L E Memory Bus Configuration register 80 Hardware Reference NS9215...
Page 136: ...WOR KI N G W I TH T H E C P U Noncachable instruction fetches 136 Hardware Reference NS9215...
Page 202: ...S Y S T E M C O N T RO L M OD U L E RTC Module Control register 202 Hardware Reference NS9215...
Page 354: ...E X T E R N A L D M A DMA Peripheral Chip Select register 354 Hardware Reference NS9215...
Page 472: ...R E A L TI M E C L O C K M O D U L E General Status register 472 Hardware Reference NS9215...
Page 512: ...TI M I NG Clock timing 512 Hardware Reference NS9215...
Page 515: ...PA CKA GING Processor Dimensions www digiembedded com 515...
Page 516: ...PA CKA GING Processor Dimensions 516 Hardware Reference NS9215...