Rainbow Electronics DS31256 - Manual (Page 18)

DS31256
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3.2 Serial Port Interface Signal Description
Signal Name: RC0 to RC15
Signal Description: Receive Serial Clock
Signal Type: Input
Data can be clocked into the device either on rising edges (normal clock mode) or falling edges (inverted clock
mode) of RC. This is programmable on a per port basis. RC0–RC2 can operate at speeds up to 52MHz.
RC3–RC15 can operate at speeds up to 10MHz. Unused signals should be wired low.
Signal Name:
RD0 to RD15
Signal Description: Receive Serial Data
Signal Type: Input
Can be sampled either on the rising edge of RC (normal clock mode) or the falling edge of RC (inverted clock
mode). Unused signals should be wired low.
Signal Name:
RS0 to RS15
Signal Description: Receive Serial Data Synchronization Pulse
Signal Type: Input
This is a one-RC clock-wide synchronization pulse that can be applied to the Envoy to force byte/frame alignment
alignment. The applied sync-signal pulse can be either active high (normal sync mode) or active low (inverted
sync mode). The RS signal can be sampled either on the falling edge or on rising edge of RC (
Table 3-B ). The
applied sync pulse can be during the first RC clock period of a 193/256/512/1024-bit frame or it can be applied
1/2, 1, or 2 RC clocks early. This input sync signal resets a counter that rolls over at a count of either 193 (T1
mode) or 256 (E1 mode) or 512 (4.096MHz mode) or 1024 (8.192MHz mode) RC clocks. It is acceptable to pulse
the RS signal once to establish byte boundaries and allow the Envoy to track the byte/frame boundaries by
counting RC clocks. If the incoming data does not require alignment to byte/frame boundaries, this signal should
be wired low.
Table 3-B. RS Sampled Edge
SIGNAL NORMAL RC CLOCK MODE INVERTED RC CLOCK MODE
0 RC Clock Early Mode Falling Edge Rising Edge
1/2 RC Clock Early Mode Rising Edge Falling Edge
1 RC Clock Early Mode Falling Edge Rising Edge
2 RC Clock Early Mode Falling Edge Rising Edge
Signal Name:
TC0 to TC15
Signal Description: Transmit Serial Clock
Signal Type: Input
Data can be clocked out of the device either on rising edges (normal clock mode) or falling edges (inverted clock
mode) of TC. This is programmable on a per port basis. TC0 and TC1 can operate at speeds up to 52MHz. TC2–
TC15 can operate at speeds up to 10MHz. Unused signals should be wired low.
Signal Name:
TD0 to TD15
Signal Description: Transmit Serial Data
Signal Type: Output
This can be updated either on the rising edge of TC (normal clock mode) or the falling edge of TC (inverted clock
mode). Data can be forced high.