Hi,
I am trying PIC 16F84 Microcontroller VGA interface to create a simple VGA output on my LCD monitor. According to the website, if everything is wired correctly, the large digits "4:57" will appear on the screen. However, it does not work properly.
On the first LCD monitor (19 inch LG) that I tried, once the VGA output from the circuit is fed, the LCD switched from "Check signal cable" to a black screen, then quickly to "Power Saving Mode".
On the 2nd LCD monitor (14 inch Philips) that I tried, once everything is connected, the LCD switches from "Sleep Mode" to an apparently black screen. If I observe carefully, there is a circle in very dark gray color expanding in diameter from the center of the screen until it is big enough to fill the entire LCD. The circle will then disappear and the whole LCD is black, then it will appear and grow again. This happens at approximately once per second. I traced this behavior to the presence of the HSYNC and VSYNC signals. If either is not present, the monitor will be in sleep mode (e.g. no signal source detected). The RED signal does not have any effects on this behaviour.
I have checked with an oscilloscope and all signals appear to be valid VGA signals. I have tried to ground BLUE and RED but that did not help. I have tried also various values for the resistor (0 ohm, 10k, 90ohm, 180ohm) according to various other websites. Does anyone know what else I am missing on, or do I have to try on a CRT monitor?
I am trying PIC 16F84 Microcontroller VGA interface to create a simple VGA output on my LCD monitor. According to the website, if everything is wired correctly, the large digits "4:57" will appear on the screen. However, it does not work properly.
On the first LCD monitor (19 inch LG) that I tried, once the VGA output from the circuit is fed, the LCD switched from "Check signal cable" to a black screen, then quickly to "Power Saving Mode".
On the 2nd LCD monitor (14 inch Philips) that I tried, once everything is connected, the LCD switches from "Sleep Mode" to an apparently black screen. If I observe carefully, there is a circle in very dark gray color expanding in diameter from the center of the screen until it is big enough to fill the entire LCD. The circle will then disappear and the whole LCD is black, then it will appear and grow again. This happens at approximately once per second. I traced this behavior to the presence of the HSYNC and VSYNC signals. If either is not present, the monitor will be in sleep mode (e.g. no signal source detected). The RED signal does not have any effects on this behaviour.
I have checked with an oscilloscope and all signals appear to be valid VGA signals. I have tried to ground BLUE and RED but that did not help. I have tried also various values for the resistor (0 ohm, 10k, 90ohm, 180ohm) according to various other websites. Does anyone know what else I am missing on, or do I have to try on a CRT monitor?
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