MC68181 Datasheet, PDF (105/119 Pages) Freescale Semiconductor, Inc – Advance Information ROAMING FLEX chip SIGNAL PROCESSOR

Freescale Semiconductor, Inc.
APPENDIX C
APPLICATION NOTES
RECEIVER CONTROL
Introduction
The FLEXchip IC has 8 programmable receiver control lines (S0–S7). The host has
control of the receiver warm up and shut down timing, as well as all of the various
settings on the control lines through configuration registers on the FLEXchip IC. The
configuration registers for most settings allow the host to configure:
• What setting is applied to the control lines,
• How long to apply the setting, and
• If the LOBAT input pin is polled before changing from the setting.
With this programmability, the FLEXchip IC is able to interface with many off-the-
shelf receiver ICs. For details on the configuration of the receiver control settings, see
Receiver Control Configuration Packets on page B-19.
Receiver Settings at Reset
The receiver control ports are tri-state outputs that are set to the high-impedance state
when the FLEXchip IC is reset and until the corresponding FRS bit in the Receiver
Line Control Packet is set, or until the FLEXchip IC is turned on by setting the ON bit
in the Control Packet. This allows the designer to force the receiver control lines to the
receiver off setting with external pull-up or pull-down resistors before the host can
configure these settings in the FLEXchip IC. When the FLEXchip IC is turned on, the
receiver control ports are driven to the settings configured by the Receiver Control
Configuration Packets until the FLEXchip IC is reset again.
MOTOROLA
MC68181 Technical Data Sheet
C-1
For More Information On This Product,
Go to: www.freescale.com