peb20560 Infineon Technologies Corporation, peb20560 Datasheet - Page 218

• Manufacturer Part Number: peb20560
• Description: Dsp Oriented Pbx Controller Doc
• Manufacturer: Infineon Technologies Corporation

Semiconductor Group
)
Figure 3-5
3.1.4.2
Prior to data transmission, the length of the frame to be transmitted must be programmed
via the Transmit Byte Count Registers (XBCH, XBCL). The resulting byte count equals
the programmed value plus one byte. Since 12 bits are provided via XBCH, XBCL
(XBC11… XBC0) a frame length between 1 and 4096 bytes can be selected.
Having written the Transmit Byte Counter Registers, data transmission can be initiated
by command XTF/XPD or XDD. The SACCO will then autonomously request the correct
amount of write bus cycles by activating the DRQT-line. Depending on the programmed
frame length, block data transfers of n × 32-bytes + remainder are requested every time
the 32 byte transmit pool is accessible to the DMA-controller.
The following figure gives an example of a DMA driven transmission sequence with a
frame length of 70 bytes, i.e. programmed transmit byte count (XCNT) equal 69 bytes.
Figure 3-6
Serial
Interface
SACCO
CPU
Interface
Serial
Interface
SACCO
CPU
Interface
Data Transmission in DMA-Mode
32 Bytes
XCNT = 69
Interrupt Driven Transmission Sequence Example
DMA Driven Transmission Example
WR
WR;
XTF
XTF
XPR
DRQT (32)
32 Bytes
WR
WR
32
Command
XTF
Transmit Frame (70 Bytes)
3-12
DRQT (32)
WR
XPR
32
Transmit Frame (70 Bytes)
6 Bytes
DRQT (6)
WR
WR
32
Operational Description
32
XTF + XME
6
6
PEB 20560
XPR
XPR
ITD05848
ITD08036
2003-08