How to wire both LCD screen and RFM12B transceiver on RPi?

[jmatsushita]

Hi @Ashure

The Tontec 2.3 inch LCD uses the pins 1 to 26 of the Pi B+ 40 pin GPIO. It uses SPI (http://www.itontec.com/download/). I'm downloading their huge documentation file to see if I can gather info about whether its using the serial port.

Can we use the remaining GPIO pins to wire the OEM RFM12B board if the screen doesn't use the UART? It seems that although there are to UARTs on the RPiB+ the second one is not wired to the GPIO header so maybe it could work in the future if we do our own pi-clone, but for now there seems to be ways to do a software based virtual serial interface interface. But it seems that doing bit banging without a real time OS is no good so it needs another microcontroller.

What do you think is the best way we could use both screen and RFM12Pi?

Best,

Jun

[jmatsushita]

This is what the documentation for the screen says:

Serial Port Demo (the serial port works as console debug output)

The image we provided is used by taking the serial port as a terminal debugging by default; in order to make it convenient for those students who can also control the raspberry pi via serial terminal even they don’t have a screen, firstly connect the DVK512 to the PC via a USB cable, and install a driver. The simplest way is to find a ”Driver Genius Professional" software on the web directly; this software will help you install the driver automatically. Or you can also use the cp2102_Driver. Zip driver under directory "software" in the CD.

Short CP_TX and RX, CP_RX and TX of the UART_JMP.

What does this mean? Can we just solder the RFM12B TX and RX to the back of the Pi?

Launch putty.exe under directory of “software”, select corresponding COM on”1”, and set Baud rate as 115200 on ”2”, then click “open” on “3”; Then enter the software, connect the raspberry pi to the electricity and start it, the software terminal will display system information, and then appear a pop-up window for you to enter user name and password;

User name: pi
Password: raspberry
Now you can enter the console terminal.

Serial Port Demo (control peripherals via Serial port communication)

The image we provided is used by taking the serial port as a terminal debugging by default; so the serial port is occupied by the system, which cannot be worked as normal serial port, When using LCD to display,

On the LXTerminal, enter:
DIS_UART-LCD

If use the HDMI output to display,
On the LXTerminal, enter:
DIS_UART-HDMI
The system restarts, disable the serial port to work as terminal debugging output, now it can be used as a normal serial port. Connect the DVK512 to the PC using a mini USB cable, open the serial port monitoring software on another computer, select baud rate as 115200;

On the LXTerminal, enter
UART_Test

A string of words will be printed on the serial port monitoring software, and what you send through the serial port monitoring software, what will be displayed on the serial port monitoring software. Press "Ctrl + C" to end the demo.
If you want to turn on the terminal debugging output function of the serial port again, you can re-enter the following command on the terminal:
When using LCD to display,

On the LXTerminal, enter:
EN_UART-LCD
when using HDMI output to display,

On the LXTerminal, enter:
EN_UART-HDMI
After entered, the system will reboot and turn on this function.

[jmatsushita]

Or maybe we should use one of these? https://lowpowerlab.com/shop/index.php?_route_=moteinousb But it seems that they don't make it in RFM12, only RFM69. Is that compatible? It would help with #3...

[shulter]

What does this mean? Can we just solder the RFM12B TX and RX to the back of the Pi?

Yes, either that or

• an intermediate shield/cape that breaks out the suitable pin header for the RFM12pi or
• a USB-serial adapter wired to the RFM12pi or
• a custom PCB as a plug and play solution for USB, possibly in a later iteration, which would be also suitable for the RFM69X

Or maybe we should use one of these? https://lowpowerlab.com/shop/index.php?_route_=moteinousb But it seems that they don't make it in RFM12, only RFM69. Is that compatible? It would help with #3...

That would work if the firmware of the rfm12pi is ported to work on the Moteino (altering the pins should suffice?)

AFAIK The RFM69 are backwards compatible with the cheaper RFM12b. They have additional features like RSSI (signal strength) and I guess a tiny bit more output power, although at these low data rates, it doesn't seem to make a difference.

[jmatsushita]

an intermediate shield/cape that breaks out the suitable pin header for the RFM12pi or

That seems good at this prototyping stage. Could you hack one for me? Wondering if it will fit.

[shulter]

Seems impossible to squeeze everything into the case then? The RFM12pi is just too high with the header.
I could design a PCB, but there is a lead time with that. The easiest solution for you would be to use an FTDI/2303HX/CP... USB adapter between the rPi and RFM12pi.