
Data Sheet
March 2000
DSP1627 Digital Signal Processor
Lucent Technologies Inc.
67
7 Mask-Programmable Options
The DSP1627 contains a ROM that is mask-programmable. The selection of several programmable features is
made when a custom ROM is encoded. These features select the input clock options, the instruction/coefficient
memory map option, and the hardware emulation or ROM security option, as summarized in Table 59.
7.1 Input Clock Options
For all input options, the input clock CKI can run at some fraction of the internal clock frequency by setting the PLL
multiplication factors appropriately (see Section 4.12, Clock Synthesis). When the PLL is bypassed, the input clock
CKI frequency is the internal clock frequency.
If the mask option for using an external crystal is chosen, the internal oscillator may be used as a noninverting input
buffer by supplying a CMOS level to the CKI pin and leaving the CKI2 pin open.
7.2 Memory Map Options
The DSP1627 offers a DSP1627x36 or a DSP1627x32 where the difference is in the instruction/coefficient memory
maps. The DSP1627x36 contains 36 Kwords of internal ROM (IROM), but it doesn’t support the use of IROM and
external ROM (EROM) in the same memory map. The DSP1627x32 supports the use of only 32 Kwords of IROM
with 16 Kwords of EROM in the same memory map. See Section 4.4 Memory Maps and Wait-States for further de-
scription.
7.3 ROM Security Options
The DSP1600 Hardware Development System (HDS) provides on-chip in-circuit emulation and requires that the re-
locatable HDS code be linked to the application code. This code's object file is called 1627hds.v#, where # is a
unique version identifier. Refer to the DSP1627-ST software tools release for more specific information. If on-chip
in-circuit emulation is desired, a nonsecure ROM must be chosen. If ROM security is desired with the DSP1627, the
HDS cannot be used. To provide testing of the internal ROM contents on a secure ROM device, a cyclic redundancy
check (CRC) program is called by and linked with the user's source code. The CRC code resides in the first
4 Kwords of ROM.
See the DSP1600 Support Tools Manualfor more detailed information.
Table 59. DSP1627 ROM Options
Features
Input Clock
Options
CMOS Level
Small Signal
Crystal
DSP1627x36
DSP1627x32
Nonsecure
Secure
Comments
2.7 V, 3.0 V, and 5.0 V.
2.7 V, 3.0 V, and 5.0 V.
2.7 V, 3.0 V, and 5.0 V.
36 Kwords IROM, no EROM in MAP1 or MAP3.
32 Kwords IROM, 16 Kwords EROM in MAP1 and MAP3.
Specify and link
1627hds.v#
*
, allows emulation.
Specify and link
crc16.v#
, no emulation capability.
Memory Map
ROM Security
*
1627hds.v#
(# indicates the current version number) is the relocatable HDS object code. It uses approximately 140 words
and must reside in the first 4 Kwords of ROM.
crc16.v#is the cyclic redundancy check object code. It uses approximately 75 words and must reside in the first 4 Kwords
of ROM. See the DSP1600 Support Tools Manual or detailed information.