Rockwell RFX144V24-S23, Руководство дизайнера

Страница: 63 / 198

RFX144V24-S23 and RFX96V24-S23 Modem Designer’s Guide
1070 3-29
3.2.10 Power-On/Reset DSP Test Mode and Crystal Selection
After Power-on or Reset, the modem enters into a test mode and calculates checksums on ROM, RAM and multiplier
sections. The results of the checksums and ASCII values corresponding to the DSP device part number and code revision
letter are written to the interface memory registers 10h through 19h approximately 20 milliseconds after Power-on/Reset
signal goes off (see Table 3-3). The contents will remain in these registers for about 4 ms or until register 10 is read by the
host.
Table 3-3. Power-On Reset Self-Test Values
Contents Register (Hex) Value (Hex)
Multiplier checksum upper word
19 46
Multiplier checksum lower word 18 EE
RAM checksum upper word 17 A0
RAM checksum lower word 16 86
ROM checksum upper word 15 36
ROM checksum lower word 14 37
DSP device upper number ASCII “0” 13 30
DSP device lower word ASCII “2” 12 32
ASCII value for “ “ (space) 11 20
DSP device code revision number (example = “A”) 10 41
To choose the 53.760 MHz crystal, bit (01:6) must be set within 4 ms after the self test results are written to the interface
memory registers and before the contents of register 10 are read. If no action is taken, the default 49.920 MHz crystal is
selected.