cx28500 Mindspeed Technologies, cx28500 Datasheet - Page 114

• Manufacturer Part Number: cx28500
• Description: Cx28500 Multichannel Synchronous Communications Controller
• Manufacturer: Mindspeed Technologies

Table 6-28.
The bit fields OOFIEN and OOFABT are related to each other in the following manner:
1. If both are 0: the signal ROOF is ignored by CX28500’s Rx side. This is the correct programming for TSBUS
2. If both are 1: this is the case of OOF functionality with OOF interrupt. CX28500 interrupts the Host and
3. If OOFABT is 1 and OOFIEN is 0: CX28500 as the case of both 1s except that no interrupt is generated.
4. If OOFIEN is 1 but OOFABT is 0: This is the case where the ROOF pin is used as a general purpose interrupt
6.6.8
The RSLP Maximum Message Length register, defined in
message length: MAXFRM1, MAXFRM2, and MAXFRM 3. Their structure is shown in the RSLP Channel
Configuration register. The minimum message length is either 1, 3, or 5 depending on protocol mode: no FCS, 16-
bit FCS, or 32-bit FCS, respectively. In the case of a short message, data is not transferred into shared memory
and is discarded. In addition, an interrupt descriptor is generated toward the Host indicating the same error
condition.
Each receive channel either selects one of these message length values or disables message length checking
altogether.
The MAXSEL bit field (see
used for received message length checking. If CX28500 receives a message exceeding the allowed maximum, the
current message processing is discontinued and terminates further transfer of data to shared memory. In addition,
28500-DSH-002-C
0
FOOTNOTE:
(1)
Bit
It is not allowed to change configuration of the port while the port is enabled. Therefore, it is not allowed to disable the port and change
configuation in the same operation. It is also not allowed to change configuation and enable the port in the same operation. Both actions
need to be split to 2 seperate operations. If the port is active one must first clear the RXENBL bit, and only then write new configuration.
If the port is inactive, one must first write new configuration with the RXENBL bit cleared and then re-write the register with the same
configuration but with the RXENBL bit set.
mode or when the ROOF pin is used as CTS or not connected at all.
executes the appropriate behavior in the channels affected by the OOF. In addition, an OOF interrupt is
generated and later an OOF recovery interrupt when the OOF condition ends.
pin. CX28500 Rx blocks ignore the ROOF signal but an interrupt to the Host is generated when the ROOF
transitions from high to low.
RSIU Port Configuration Register (3 of 3)
NOTE:
Field Name
RSLP Maximum Message Length Register
RCOFAIEN
Table 6-23, RSLP Channel Configuration
For polling to work properly and efficiently, it is mandatory that the FIRST (receive time
slot)/LAST (transmit time slot) indications be configured for each channel regardless of the
operational mode (i.e., HDLC, transparent, etc.). The polling mechanism in the CX28500
uses these markings as triggering points. When configured correctly, CX28500 polls on a
channel once at the selected poll throttle rate instead of polling at every time slot allocated
to that channel, as in the case of hyperchannels. When a channel consists of only one time
slot, as in a DSO channel, its corresponding receive time slot should have the FIRST_TS bit
set. Likewise, its corresponding transmit time slot should have the LAST_TS bit set.
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Value
0
1
Change Of Frame Alignment/Recovery from Change Of Frame Alignment Interrupts
Disabled.
Change Of Frame Alignment/Recovery from Change Of Frame Alignment Interrupts
Enabled. If COFA is detected, generate Interrupt indicating COFA. When COFA is
recovered from, generate a Recovery From COFA Interrupt indication.
Table
6-29, can have three separate values for maximum
®
Register) selects which (if any) register is
Description
Memory Organization
99