cx28500 Mindspeed Technologies, cx28500 Datasheet - Page 80

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

Figure 5-2.
The frequency of polling is controlled independently for each port by the RPOLLTH or TPOLLTH bit fields in RSIU
Port Configuration register and TSIU Port Configuration register (poll throttle) bit fields in
Configuration Register
direction.
The RPOLLTH or TPOLLTH bit fields in RSIU Port Configuration register and TSIU Port Configuration register, bit
field specifies how often CX28500 checks the owner bit in a Host-owned Buffer Descriptor. The values correspond
to 1, 2, 4, 8, 16, 64, 128, and 256 frame periods.
If the serial port is configured to unchannelized mode, this mechanism is still implemented. The user programs the
Section 6.7.6
1. Program the STARTAD to point to the single entry that is used for this port in the Time Slot Configuration
28500-DSH-002-C
Descriptor.
CH_ACT
(for the transmit) or
TDMA State Machine
NOTE:
Descriptor
Message
Pointer
Read
Read
Head
(MD)
for the Rx direction and
Poll (NP = 0)
CX28500 Owned
(Owner = 1)
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.
Section 6.6.6
CH_JUMP
Host - Owned
CH_ACT
Poll (NP = 0)
Mindspeed Proprietary and Confidential
(Owner = 0)
Mindspeed Technologies
While there is an EOM and EOB
Descriptor
Buffer
(BD)
Poll
INHTBSD = 1
(for the receive) as follows:
Table 6-36, TSIU Port Configuration Register
CX28500 - Owned
Suspend
TDMA
State
CX28500 Owns
Owner = 1
the BD
(Owner = 0 NP=1 0
Host-Owned
EOM
Not
an ONR Interrupt
if TONRIEM = 1
is Generated
®
ONR
Read
Data
EOB
Not
TxONR
INHTBSD = 0
(Allow Status
EOM or
EOB
Write)
Always
Table 6-28, RSIU Port
Buffer Status
Descriptor
(BSD)
Write
Serial Interface
for the Tx
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