ST7920-0C View Datasheet(PDF) - Sitronix Technology Co., Ltd.
Part Name
Description
MFG CO.
'ST7920-0C' PDF : 49 Pages View PDF
ST7920
Application circuit for testing CGROM and HCGROM:
We can use the function of “CHECK SUM” to check the CGROM is right or error.
See the following notes: Useing IC Pad (Pin4àCLK, Pin5àTT1, Pin6àTT2) to do the “CHECK SUM” function.
The application circuit is at Page49.
Timing Diagram for checking CGROM (TT1=0, TT2=1)
The ST7920 check sum process: (DDRAM must be cleared by 0x00 before this process)
In the first place: Resetting the internal counter (set TT1 and TT2 to Height)
In the second place: Setting CGROM mode (set TT1 to Low, TT2 to Height).
In the third place: CLK starts to count 655362 times.
In the final place: Finishing the counting, read the last four bytes to CHECK SUM (reading only when the CLK is
Height).
ST7920 check sum circuit: Data is available when CLK is height; if CLK is low then the data is always FFH. The last
four bytes are Y0, Y1, Y2, and Y3.
The fatest execution time is: tCYC=1us (1MHz at 5V).
The table below is a comparing table of CGROM for different versions.
Version
(Font)
1 Big5 (0A)
2 GB (0B)
CGROM Last four bytes
Y0
Y1
Y2
Y3
38
88
CC
F1
9D
81
79
29
3 0C
FD
6F
B5
85
V4.0
28/49
2008/08/18
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