Figure 7-12 Crb Syn Bit Operation - Motorola DSP56309 User Manual

Enhanced Synchronous Serial Interface (ESSI)
ESSI Programming Model
7.4.2.12 CRB ESSI Mode Select (MOD) Bit 13
MOD selects the operational mode of the ESSI; see Figure 7-13 on page 7-21, Figure 7-14
on page 7-22, and Figure 7-15 on page 7-23. When MOD is cleared, normal mode is
selected; when MOD is set, network mode is selected. In normal mode, the frame rate
divider determines the word transfer rate: one word is transferred per frame sync during
the frame sync time slot. In network mode, a word can be transferred every time slot. For
more details, see Section 7.5ÑOperating Modes. Either a hardware RESET signal or a
software RESET instruction clears MOD.
External Transmit Clock
SC
Internal Clock
ESSI Bit
Clock
External Receive Clock
SC0
NOTE: Transmitter and receiver can have different clocks and frame syncs.
External Clock
SCK
Internal Clock
ESSI Bit
Clock
NOTE: Transmitter and receiver can have the same clock frame syncs.
7-20
Asynchronous (SYN = 0)
Transmitter
Clock
Clock
RECEIVER
SYNCHRONOUS (SYN = 1)
Transmitter
Clock
Clock
Receiver

Figure 7-12 CRB SYN Bit Operation

DSP56309UM/D
STD
Frame
SYNC
External Transmit Frame SYNC
Internal Frame SYNC
External Receive Frame SYNC
Frame
SYNC
SRD
STD
Frame
SYNC
External Frame SYNC
Internal Frame SYNC
Frame
SYNC
SRD
SC2
SC1
SC2
AA0682
MOTOROLA