05-16-2012 11:31 PM
I want to display an internal "counter" to the LCD on the Spartan 3E starter kit. I am currently being able to print a fixed string, and I am familiar with the basic LCD operation.
To display a counter, the DB7:DB4 are not fixed but dependent on the counter value. So, instead of going through a "case" and finding out what the counter bit is and then using the corresponding bits from CG-ROM and printing it on the LCD, is there a direct/indirect way to display the counter?
Note that I am using verilog as my HDL language and what needs to be printed is a number/counter.
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05-17-2012 06:54 AM
is there a direct/indirect way to display the counter?
Let's assume the counter is 8 bits wide, and you want to display the counter's 8-bit value as 2 hexadecimal (range 0-9 + A-F) characters.
- From Table 4 of the HD44780U data sheet we see that the displayed characters '0'-'9' are represented by character codes 0x30-0x39.
- From Table 4 of the HD44780U data sheet we see that the displayed characters 'A'-'F' are represented by character codes 0x41-0x46.
- To each of the 4-bit portions of the 8-bit counter value, add 0x30. If the result is greater than 0x39, then add another 0x07.
- The resulting sum is what you should 'send' to the LCD (actually, you are sending it to the HD44780U LCD controller).
Does this make sense?
-- Bob Elkind
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