Datasheet

DS2250(T)
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PROGRAM LOADING
The Program Load Modes allow initialization of the NV RAM Program/Data Memory. This initialization
may be performed in one of two ways:
1. Serial Program Loading which is capable of performing Bootstrap Loading of the DS2250(T). This
feature allows the loading of the application program to be delayed until the DS2250(T) is installed in
the end system.
2. Parallel Program Load cycles which perform the initial loading from parallel address/data information
presented on the I/O port pins. This mode is timing set-compatible with the 87C51H microcontroller
programming mode.
The DS2250(T) is placed in its Program Load configuration by simultaneously applying a logic 1 to the
RST pin and forcing the PSEN line to a logic 0 level. Immediately following this action, the DS2250(T)
will look for a parallel Program Load pulse, or a serial ASCII carriage return (0DH) character received at
9600, 2400, 1200, or 300 bps over the serial port.
The hardware configurations used to select these modes of operation are illustrated in Figure 3.
PROGRAM LOADING CONFIGURATIONS Figure 3