PCB Fab LCD (HD44780) via serial ATMEGA168

[ashley.hughes]

Hey,

I have done up the 1st version of my Serial LCD board, that I am gonna get it fabricated.

I just wanna know if my schematic is correct in particular the FTDI connection part, I will be putting the Arduino boot-loader on the ATMEGA168 running a custom sketch. I will upload the sketch by my FTDI board (http://www.sparkfun.com/products/10008)

I plan on connecting this board to another Arduino project and updating the display by sending data to the LCD board via the TX line to the RX line on the LCD board. It will be powered off the main arduino, so I am not placing a voltage reg on this board yet.

Here is my 1st design I have swapped the RX and TX from the FTDI to the ATMEGA168 to program it.



The main reason is to free up pins off my main Arduino.

If anyone has any comments that might help make it better or if it is not going to work please let me know

[aluck]

I don't get the point of this project - why not use just one I2C port expander instead of mega8?

[Psi]

It does have its advantages.

You can add some smarts to the ATmega in order to simply communication.
Make your own LCD API that can do animations and stuff without loading the cpu time of the main micro. etc.

Not that a 2 line text lcd is cpu intensive, but it's a really good learning experience to do micro <-> micro communications and write your own protocols
A lot of new hobbies tend to stick to a single micro and just play around with adding hardware to it.

hehe, you're not a real microcontroller programmer until you've got multiple micros talking to each other 

[aluck]

You can add some smarts to the ATmega in order to simply communication.
Make your own LCD API that can do animations and stuff without loading the cpu time of the main micro. etc.

yes, but then you have to bother with actual programming firmware on the secondary CPU, and you still have to do interaction between them. from a practical point of view it is just not economically viable

[Psi]

You can add some smarts to the ATmega in order to simply communication.
Make your own LCD API that can do animations and stuff without loading the cpu time of the main micro. etc.

yes, but then you have to bother with actual programming firmware on the secondary CPU, and you still have to do interaction between them. from a practical point of view it is just not economically viable

I don't think he's doing it to be economical, I think he's doing it for fun and to learn.

[Psi]

One thing i see missing is a programming connector to access RESET/MOSI/MISO/SCK/GND.

Unless you plan to use a DIP IC with a socket?

[aluck]

One thing i see missing is a programming connector to access RESET/MOSI/MISO/SCK/GND.

Unless you plan to use a DIP IC with a socket?

I would put ISP connector anyway. And I would try to throw out the quartz.

[ashley.hughes]

I am going to program it via the FTDI, I could bring out the ISP connectors for future. it will be in a DIP socket. I will also bring out most of the spare pins to headers as well to allow me to easily add more functions.

Through out the quartz? They are so cheap and that means that I will have to change fuzes when I burn the bootloader. I am gonna burn it through the Arduino IDE using a Arduino as the ISP as I dont have a programmer so the less I have to change the easier.

[shebu18]

For arduino use put a cap between the reset line, like in the schematic.  http://arduino.cc/en/uploads/Main/arduino-duemilanove-schematic.pdf

[alm]

I would keep the crystal if you're using async serial, the internal RC oscillator can't reliably meet the accuracy required for RS-232.

[ashley.hughes]

I read some where about the cap on the reset line, in the tutorial that I read for how to move a Arduino to the breadboard they recommend a Resistor. I might put a cap in there as it is more common if I have problems I can put a resistor in. I will put a space for both on the design though.

The place I get the board from does three boards for each design that you give him. Try both :p

The crystal is going to stay cause it is cheap as chips and I am going to be using UART and I am sure that it will help