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Because the RISM begins at location 2000H in serial port programming mode, the OTPROM lo-
cations are automatically remapped as shown in Table 15-11. For example, to access OTPROM
location FF2000H in serial port programming mode, you must address it as A000H.
Table 15-11. 87C196NT Serial Port Programming Mode Memory Map
Description
Internal OTPROM
External memory
Do not address
Test ROM and RISM
†
The lower 24 Kbytes of internal OTPROM (FF2000–FF7FFFH) are remapped to A000–FFFFH.
The upper 8 Kbytes (FF8000–FF9FFF) must be addressed as 8000–9FFFH.
15.10.2 Changing Serial Port Programming Defaults
Several locations in test ROM are used to control operating parameters. The test ROM routine
establishes the default values shown in Table 15-12. To change the default values, write the de-
sired values to the test ROM addresses shown in the table. (Refer to the SP_BAUD and SP_CON
register descriptions in Appendix C and the SP_PPW description on page 15-9.) After you write
the new values to the test ROM locations, the RISM writes the programmed values into the asso-
ciated registers.
The default programming pulse width is longer than required. To avoid unnecessarily long pro-
gramming times, change the default value before beginning to program the device. For a 100-µs
pulse width, use the following formula to determine the required PPW_VALUE and write that
value to the test ROM location listed in Table 15-12.
(
PPW_VALUE
=
Table 15-12. 87C196NT Serial Port Programming Default Values and Locations
Parameter
Mode
09H; mode 1, receiver enabled
Baud rate
8067H; 9600 baud at 16 MHz
Pulse width
80FFH; 2.30ms per pulse at 16 MHz
Normal Operation
FF2000–FF9FFF
—
—
—
×
)
0.6944
F
1
–
osc
RISM Default
PROGRAMMING THE NONVOLATILE MEMORY
Address Range (Hex)
Serial Port Programming Mode
A000–FFFF, 8000–9FFF
Test ROM Address
2215H
2216H
221C–221DH
†
4000–9FFF
2400–3FFF
2000–23FF
SFR
SP_CON
SP_BAUD
SP_PPW
15-33
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