9 $1839; DB2; TIED LOW TO DGND
10 $1838; DB3; TIED LOW TO DGND
11 LCD_D4
12 LCD_D5
13 LCD_D6
14 LCD_D7
15 $1830; LCD BACKLIGHT ANODE (A) TO
+5VD THRU 100 OHMS
16 LCD BACKLIGHT CATHODE (K) TO
DGND
Table 1: LCD header signals
The flowchart in Figure 3, below, walks through troubleshooting LCD issues beginning
with the error code explained above. If identified as error code 0x11, the pins on the
LCD need to be looked at with the scope according to the order in the flowchart. A scope
set with 2 V/div and 5 µsec/div should be able to capture the toggling on the lines
identified in the flowchart.
As a reference, examples of the scope displaying toggling bits on different lines can be
seen in Figures 4-6, below. The unit in the example displayed toggling on the LCD_EN,
LCD_RW, and data lines but NOT on the LCD_RS line, therefore it was concluded and
verified that something was wrong with the LCD_RS line. In this particular case, the
microcontroller (U706) pin 51 was not soldered.
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