Serial Interface
MPC885 PowerQUICC Family Reference Manual, Rev. 2
Freescale Semiconductor
20-27
20.2.5
IDL Bus Implementation
The full-duplex ISDN interchip digital link (IDL) interface connects a physical layer device to the
MPC885. The basic and primary rate of the IDL bus is supported by the MPC885. In the basic rate, data
on three channels (B1, B2, and D) is transferred in a 20-bit frame, providing a full-duplex bandwidth of
160 Kbps. The MPC885 is an IDL slave device that is clocked by the IDL bus master (physical layer
device) and has separate receive and transmit sections. Using both TDMs, the MPC885 supports two
independent IDL buses as shown in
Figure 20-24
.
Figure 20-24. Dual IDL Bus Application Example
20.2.5.1
ISDN Terminal Adaptor Application
An example IDL application is the ISDN terminal adaptor shown in
Figure 20-25
. In such an application,
the IDL interface connects the 2B+D channels between the MPC885, CODEC, and S/T transceiver. An
SCC is configured in HDLC mode to handle the D channel. Another SCC is used to rate adapt the terminal
10
The simplest configuration—each pointer is used continuously and has only one function.
RaPTR points to the active Rxa entry and RbPTR points to the active Rxb entry.
TaPTR points to the active Txa entry and TbPTR points to the active Txb entry.
11
Each pointer is used continuously. The section of SI RAM it points to depends on whether its value is in the first
half (0–15) or the second half (16–31).
• RaPTR points to the active Rxa entry. If RaPTR = 0–15, the current-route RAM is SI RAM address block
0–63 and SISTR[CRORa] = 0. If RaPTR = 16–31, the current-route RAM is SI RAM address block 64–127
and SISTR[CRORa] = 1.
• RbPTR points to the active Rxb entry. If RbPTR = 0–15, the current-route RAM is SI RAM address block
128–191 and SISTR[CRORb] = 0. If RbPTR = 16–31, the current-route RAM is SI RAM address block
192–255 and SISTR[CRORb] = 1.
• RaPTR points to the active Txa entry. If TaPTR = 0–15, the current-route RAM is SI RAM address block
256–319 and SISTR[CROTa] = 0. If TaPTR = 16–31, the current-route RAM is SI RAM address block
320–383 and SISTR[CROTa] = 1.
• TbPTR points to the active Txb entry. If TbPTR = 0–15, the current-route RAM is SI RAM address block
384–447 and SISTR[CROTb] = 0. If TbPTR = 16–31, the current-route RAM is SI RAM address block
448–511 and SISTR[CROTb] = 1.
Table 20-10. SIRP Pointer Values (continued)
RDM
Configuration
S/T
S/T
U
U
S/T
S/T
IDL1
S/T
Interfaces
IDL2
ISDN TE
NT
U
Interfaces
MPC885
Summary of Contents for PowerQUICC MPC870
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Page 118: ...MPC885 Overview MPC885 PowerQUICC Family Reference Manual Rev 2 1 20 Freescale Semiconductor ...
Page 158: ...The MPC8xx Core MPC885 PowerQUICC Family Reference Manual Rev 2 3 18 Freescale Semiconductor ...
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Page 1090: ...UTOPIA Interface MPC885 PowerQUICC Family Reference Manual Rev 2 43 8 Freescale Semiconductor ...
Page 1312: ...Byte Ordering MPC885 PowerQUICC Family Reference Manual Rev 2 A 8 Freescale Semiconductor ...
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Page 1370: ...MPC880 MPC885 PowerQUICC Family Reference Manual Rev 2 E 4 Freescale Semiconductor ...
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