2) Can I use this RD pin if I solder a wire from it to an unused Arduino pin (such as #44 for example) ?
Ok I ask this because if they haven't connected it to a useable pin when designing that shield, that's probably for a good reason no?
To avoid unnecessarily tying up an Arduino I/O pin for a capability that is rarely used.
they could have used them anyway
Not a whole lot of thoughts went into designing those products.
Hello, I have Sainsmart's 3.2" TFT display and adapter shield for Arduino MegaI need to read data from GDDRAM, (to retrieve pixel color), in order to do that, I need to use the RD (Data Read) pin..which unfortunately isn't useable, look this picture:
Yes that's correct - the RD line must be wired high in serial mode (SPI) - you can't read except in one of the parallel modes. This isexplained in the datasheet in "Table 2 Pin Function Description".From what I can see of that adapter it uses the SPI bus - if so then you can't read the graphics memory.