DS2250(T)
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The Parallel Program cycle is used to load a byte of data into a register or memory location within the
DS2250(T). The Verify cycle is used to read this byte back for comparison with the originally loaded
value to verify proper loading. The Security Set cycle may be used to enable and the software security
feature. One may also enter bytes for the MCON register or for the five encryption registers using the
Program MCON cycle. When using this cycle, the absolute register address must be presented at Ports 1
and 2 as in the normal program cycle (Port 2 should be 00H). The MCON contents can likewise be
verified using the Verify MCON cycle.
When the DS2250(T) first detects a Parallel Program Strobe pulse or a Security Set Strobe pulse while in
the Program Load Mode following a power-on reset, the internal hardware of the device is initialized so
that an existing 4-kbyte program can be programmed into a DS2250(T) with little or no modification.
This initialization automatically sets the range address for 8 kbytes and maps the lowest 4-kbyte bank of
embedded RAM as program memory. The next 4 kbytes of embedded RAM are mapped as data memory.
In order to program more than 4 kbytes of program code, the Program/Verify Expanded cycles can be
used. Up to 32 kbytes of program code can be entered and verified. Note that the expanded 32 kbyte
Program/Verify cycles take much longer than the normal 4 kbyte Program/Verify cycles.
A typical parallel loading session would follow this procedure. First, set the contents of the MCON
register with the correct range and partition only if using expanded programming cycles. Next, the
encryption registers can be loaded to enable encryption of the program/data memory (not required). Then,
program the DS2250(T) using either normal or expanded program cycles and check the memory contents
using Verify cycles. The last operation would be to turn on the security lock feature by either a Security
Set cycle or by explicitly writing to the MCON register and setting MCON.0 to a 1.
SERIAL LOADER BAUD RATES FOR
DIFFERENT CRYSTAL FREQUENCIES Table 2
BAUD RATE
CRYSTAL FREQ
(MHz)
300 1200 2400 9600 19200 57600
14.7456 Y Y Y Y
11.0592 Y Y Y Y Y Y
9.21600 Y Y Y Y
7.37280 Y Y Y Y
5.52960 Y Y Y Y
1.84320 Y Y Y Y
ADDITIONAL INFORMATION
A complete description for all operational aspects of the DS2250(T) is provided in the Secure
Microcontroller User’s Guide.
DEVELOPMENT SUPPORT
The DS89C450-K00 evaluation kit can be used to develop and test user code. It allows the user to
download Intel hex formatted code to the DS2250(T) from a PC. The user must purchase the DS2250 and
DS9072-40V mechanical adapter separately. Refer to the Secure Microcontroller User’s Guide for further
details.
