CMX980AL7 CML Microcircuits, CMX980AL7 Datasheet - Page 81

• Manufacturer Part Number: CMX980AL7
• Description: TETRA Baseband Processor
• Manufacturer: CML Microcircuits

TETRA Baseband Processor
PAGE 1 ADDRESSED REGISTERS
Title:
Address:
Function:
Description:
1999 Consumer Microcircuits Limited
DirectWrite79tapI
Direct write access to 79-tap I channel filter
$0x20 - $0x2F (16 locations)
RW
These registers are the direct access points to the 79-tap filter I channel. Writing accesses the
holding latch whose value is transferred to the filter input at the next internal sample clock
enable time. Read the address returns the value of the holding latch.
To allow the data latch value into the filter the TxDirectWriteEn bit must be set in the TxSetup
Register otherwise the input data for the filter is taken from the DQPSK modulator output.
These registers can be read via two operations, giving the most significant nibble and least
significant byte respectively. In the read case, the D11 bit becomes an address bit, which is
used to select between the most significant nibble (D11 = ‘1’) and the least significant byte (D11
= ‘0’). The D10, D9 and D8 bits are ignored.
The format for write data is to apply the most significant 4 bits of the data value to the address
field [3:0] and the least significant 8 bits to the data field [7:0]. In this way a 12-bit value can be
written in one serial operation.
81
CMX980A
D/980A/3