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Topic: Has anyone got these cheap LCD's to work with arduino? (ST7735R) (Read 9416 times) previous topic - next topic

Docedison

No the ST7735 driver is an SPI device only. The more expensive of the two form OP's post is identical to one from Adafruit to the SD card and footprint for the 8 pin eprom on the back side. the real difference is the $15.00 price difference.

Bob
--> WA7EMS <--
"The solution of every problem is another problem." -Johann Wolfgang von Goethe
I do answer technical questions PM'd to me with whatever is in my clipboard

dtokez

#16
Jan 12, 2013, 02:30 am Last Edit: Jan 12, 2013, 03:46 am by dtokez Reason: 1
EDIT: Done some more searching (a lot more lol) and managed to work out the wiring, and also get the adafruit libs installed and now it is working, very impressive little screen!

Hi all. The display has just arrived :) I got one of these http://www.ebay.co.uk/itm/1-8-Serial-128X160-SPI-TFT-LCD-Module-Display-PCB-Adapter-SD-Socket-/261150773094

I'm not sure how to wire it up though :( Just looked at the adafruit tutorial and the board has different pin definitions?


dtokez

OK, first question has arisen already  :smiley-roll-sweat:

I notice when you send data to the screen it stays until something is written over it. When sending variable data text strings to the TFT, the results just keep overlaying each other. Sending
Code: [Select]
tft.fillScreen(ST7735_BLACK); is very slow and it seems pointless re-writing any static text also.

Is there a simple way around it? I guess you could just write black squares over areas but that sounds like a nightmare to implement :(

Also the wrong as some of you mentioned would be the case.

zachwiej

There is a method to speed up communication
In Adafruit_ST7735.cpp search for
SPI.setClockDivider(SPI_CLOCK_DIV4);

and change it to
SPI.setClockDivider(SPI_CLOCK_DIV2);

That will speed up SPI bus

I was using it on 3.3v 8mhz atmega328p, not on 16mhz so it may not work

dtokez

Is that using the hardware SPI pins? I have just looked at the code and again and realised I am not using them?

Code: [Select]
// You can use any (4 or) 5 pins
#define sclk 4
#define mosi 5
#define cs   6
#define dc   7
#define rst  8  // you can also connect this to the Arduino reset

#include <Adafruit_GFX.h>    // Core graphics library
#include <Adafruit_ST7735.h> // Hardware-specific library
#include <SPI.h>

// Option 1: use any pins but a little slower
Adafruit_ST7735 tft = Adafruit_ST7735(cs, dc, mosi, sclk, rst);

// Option 2: must use the hardware SPI pins
// (for UNO thats sclk = 13 and sid = 11) and pin 10 must be
// an output. This is much faster - also required if you want
// to use the microSD card (see the image drawing example)
//Adafruit_ST7735 tft = Adafruit_ST7735(cs, dc, rst);

zachwiej

my code is only for hardware spi (it is 2-4 times faster than software)

Docedison

The answer to the overlaid printing is to first print a blank line over the text  you are refreshing.
Glcd.print("                    "); or something similar. I'm not at home now so I can't share the example code. If you need it I'll be happy to post it later today.

Bob
--> WA7EMS <--
"The solution of every problem is another problem." -Johann Wolfgang von Goethe
I do answer technical questions PM'd to me with whatever is in my clipboard

dtokez

@zachwiej - How do you connect up the display to the hw SPI on the arduino?

Code: [Select]
// Option 2: must use the hardware SPI pins
// (for UNO thats sclk = 13 and sid = 11) and pin 10 must be
// an output. This is much faster - also required if you want
// to use the microSD card (see the image drawing example)

I guess 13 goes to SCK on the lcd, but I'm not sure what pins 11 and 10 need to be wired to on the screen?

@Docedison - Thanks Bob I would quite like to see the code if you don't mind.


tack

Pin  10 to cS (the one for TFt, not the one in the SD section)
Pin 11 to SDA
Pin 13 to SCL

If you want to use the SD card too then also wire the MOSI, MISO and SCK from SD card connections to 11,12,13 and the CS to 4.

zachwiej


LCD MISO goes to arduino MISO, MOSI to MOSI, SCK to SCK, CS to CS and there will be one signal left so connect it to any other pin. Like in Adafruit tutorial

tack

#25
Jan 13, 2013, 12:17 pm Last Edit: Jan 13, 2013, 12:20 pm by tack Reason: 1
The TFT connections are labelled SDA, SCL, CS, AO. The SD card connections are labelled MOSI, MISO, SCK, CS.

At first glance it looks like the TFT is I2C (SDA and SCL) but these actually correspond to he TFT's MOSI and SCK inputs. AO is the DC in the Adafruit tutorial.

There are two CS, but one is clearly marked inside an area labelled 'SD' while the other (TFT) is outside that area.

dtokez

#26
Jan 14, 2013, 01:29 am Last Edit: Jan 14, 2013, 01:34 am by dtokez Reason: 1
Hi all. I'm still confused here.

I have now connected 3 data pins as such and it is not working
Pin 10 to TFT CS
Pin 11 to TFT SDA
Pin 13 to TFT SCK

Where do I connect A0 or reset? The adafruit tutorial says "sclk = 13 and sid = 11) and pin 10 must be an output".

Code: [Select]
// You can use any (4 or) 5 pins
#define sclk 1
#define mosi 5
#define cs   6
#define dc   7
#define rst  8  // you can also connect this to the Arduino reset

#include <Adafruit_GFX.h>    // Core graphics library
#include <Adafruit_ST7735.h> // Hardware-specific library
#include <SPI.h>
#include <math.h>

// Option 1: use any pins but a little slower
//Adafruit_ST7735 tft = Adafruit_ST7735(cs, dc, mosi, sclk, rst);

// Option 2: must use the hardware SPI pins
// (for UNO thats sclk = 13 and sid = 11) and pin 10 must be
// an output. This is much faster - also required if you want
// to use the microSD card (see the image drawing example)
Adafruit_ST7735 tft = Adafruit_ST7735(cs, dc, rst);


Will the above work or do I have to change the #define pins, or does something in the library set it up?

Thanks!



zachwiej

Hi
If You want to use hardware SPI use this definition (You can change those pins)
#define cs   10
#define dc   9
#define rst  8 
Adafruit_ST7735 tft = Adafruit_ST7735(cs, dc, rst);

dtokez

Thanks! it is working now, I didn't have A0 connected to pin 9 :)

I am just working on trying to get test to refresh without blanking the entire screen.

I'm trying out the following but the blank line does not appear to be printing and the variable is still getting overwritten constantly?

zachwiej

Just print the old text in white before printong new text ;) works like charm

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