5-4 Chapter 5: Programming
Reset Display
xx=microcontroller status
00=OK
If failure occurs, the firmware performs a
loop forever.
00=Ok, present
01=Not present
FF=Failure
zz=number (in hexadecimal) of character
sets available in the Flash
00=10
Description
This command executes the power–down power–up diagnostic sequence. The
communication lines (RTS for serial, BUSY for parallel) are placed in an exception
condition (see the “Diagnostics” section). The microcontroller test consists of a sum–
check test on the ROM and a write/read test on the RAM. A check–sum test is also
performed on the FLASH that holds any user defined character sets. After executing
the command, the three status bytes (see above) are sent to the host, the display screen
is cleared, the cursor moves to the 0 position, communication line exception
conditions are cleared, and all registers and variables are initialized. Note that the
screen is cleared during this command. If a host needs previous data redisplayed, the
host must resend the previous data after this command has completed. Since true bi–
directional communications are not available for the parallel interface, a unique
interface utilizing the Strobe line as a clock line and the Ack line as a data line is used.
Erase Display
Description
This command clears all of the displayed characters by writing a space to each display
position. A space is defined as character 0x20 of the current character set. The cursor
moves to the 0 position.
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