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EMX + CP7 display


#1

Hi guys,
we are using GHI EMX with T43 displays in a real-world solution - it works just fine, but our customers want bigger display. So we tried to order CP7 display, but our hardware guy is quite desperate how to connect it to our existing solution. RGB sockets are just fine, but we don’t know how to deal with I socket to handle touches. So my question is, where to connect those pins to EMX? If I look at FEZ SPIDER which have similar processor as EMX, I can connect it into HI socket, so the connection will look like this:

which is not good, because we already use IO11 and IO12 for different purposes. Is there a way to connect it to different pins and specify it to the driver?

I’m sorry, I know my question is quite confused, but I don’t know where to start, because every topics about CP7 is for gadgeteer :frowning:


#2

I am not sure where the usb came fromin your pinout. This display uses i2c bus to handle touch screen.


#3

So, to make it work, the connection should look like this:

then use code similar to this:

https://www.ghielectronics.com/community/codeshare/entry/794

I don’t understand why there are two SCL and SDA pins on I port… I use only SCL on pin 9 a SDA on pin 8, am I right?


#4

Most I2C devices only will need to use the SCL and SDA pins. The other two pins socket pin 3 and socket pin 6 are there if the I2C device has any extra features that may require pins and so with the Gadgeteer specifications, on an “I” socket, there is to be 4 pins guaranteed: An Interrupt capable GPIO pin (3), a basic GPIO (6) and the I2C bus pins, SDA (8) and SCL (9).


#5

Thank you guys. Can I have one last stupid question? I understand what are INT, SCL and SDA pins for, but what is the main purpose of RST pin in case of CP7 display?


#6

I misunderstood this statement previously. There are two I2C pins on this socket because the two I2C pins on 4 and 5 are for Software I2C. Software I2C allows the simulation of the I2C bus through GPIO pin toggling, which on most processors is as fast as the buses specification. The pins on 8 and 9 are native I2C which uses the processor’s I2C controller. It is determined in the driver which are used depending on which bus is used, software or native.

The RST pin is more than likely there to reset the module’s I2C processor; however, this is not currently supported in the driver.