PEB2035 Datasheet, PDF (63/134 Pages) Siemens Semiconductor Group – ICs for Communications (Advanced CMOS Frame Aligner)

PEB 2035
RREQ
bit EMOD.EDMA = ‘0’: at the end of the first read access to stack RSIG (rising edge of
RDQ).
bit EMOD.EDMA = ‘1’: with the beginning of the second (PCM 30) or third (PCM 24) read
access to stack RSIG (falling edge of RDQ).
This stack is addressed by
1. address ‘7’ and a read command (memory-to-memory DMA transfer)
2. signal: ACKNLQ and read command (I/O-to-memory DMA transfer)
Both requests may be triggered at the same time. The sequence of service is determined by the
user.
RDO
ACFA
PEB 2035 _XDI
SYPQ
MTSC
PEB 2045
ACKNLQ
=1
RREQ
XREQ
DMA
Controller
RMFB
XMFB
: PCM 24 only
µP-Bus
ITS03586
Figure 16
Connection to a DMA Controller
d. Access via Microprocessor
In principle, the use of the microprocessor for signaling tasks is similar to memory-to-memory DMA
applications. The request signals RREQ and XREQ indicate the meaning of interrupt requests.
Additionally, in PCM 24 mode the possibility exists to use FS/DL bits for carrying signaling
information. In this case, the signals RMFB and XMFB are used as interrupt requests.
Acknowledging is done by programming the two interrupt acknowledge bits XFDL.RMAK and
XFDL.XMAK.
Semiconductor Group
63