delays when updating the screen from digital IO

[leejsmith]

I am new to the Gameduino 3x, but have written games with normal SPI screens and use a SNES controller for input. When I read the buttons  and send to the serial terminal it's instant, but the Gameduino screen does nothing for like 3-4 seconds. if you Keep pressing it will carry on showing movements, but it has this massive delay. I looked through the forum and most people are asking about the touchscreen, but could not find much about using arduino IO to control sprites so I am a bit lost as to how to fix this delay.


#include <EEPROM.h>

#include <SPI.h>

#include <GD2.h>



int DATA_CLOCK = 35;

int DATA_LATCH = 36;

int DATA_SERIAL = 37;

int counter=0;

int buttons[12];



void setup() {

// put your setup code here, to run once:

pinMode (DATA_CLOCK, OUTPUT);

digitalWrite (DATA_CLOCK, HIGH);



/** Set DATA_LATCH normally LOW **/

pinMode (DATA_LATCH, OUTPUT);

digitalWrite (DATA_LATCH, LOW);



/** Set DATA_SERIAL normally HIGH **/

pinMode (DATA_SERIAL, OUTPUT);

digitalWrite (DATA_SERIAL, HIGH);

pinMode (DATA_SERIAL, INPUT);

GD.begin();

Serial.begin(9600);

}



void loop() {

// put your main code here, to run repeatedly:

digitalWrite(DATA_LATCH, HIGH);

delayMicroseconds(12);

digitalWrite(DATA_LATCH, LOW);

delayMicroseconds(6);



/** Read data bit by bit from SR **/

for (int i = 0; i < 16; i++) {

digitalWrite (DATA_CLOCK, LOW);

delayMicroseconds (6);

if (i <= 11) {

buttons = digitalRead (DATA_SERIAL);

}

digitalWrite (DATA_CLOCK, HIGH);

delayMicroseconds (6);

}

GD.ClearColorRGB(0x103000);

GD.Clear();

//GD.cmd_text(50, 50, 31, OPT_CENTER, String(counter));

if (buttons[4]==0) {

GD.cmd_text(GD.w / 2, GD.h / 2, 31, OPT_CENTER, "u");

Serial.print(" up ");

}

if (buttons[5]==0) GD.cmd_text(GD.w / 2, GD.h / 2, 31, OPT_CENTER, "d");

if (buttons[6]==0) GD.cmd_text(GD.w / 2, GD.h / 2, 31, OPT_CENTER, "l");

if (buttons[7]==0) GD.cmd_text(GD.w / 2, GD.h / 2, 31, OPT_CENTER, "r");

GD.swap();

}

[leejsmith]

If I start the code with a button pressed it updates the screen straight away, but if it runs before pressing anything the delay is around 66 cycles.

[leejsmith]

ok, after some more testing I found that adding GD.get_inputs(); fixed the delay even though I am not using the inputs from the Gameduino.

[leejsmith]

A quick Demo
imgur.com/a/Tt9Sy0A

[jamesbowman]

Right, the thing about the 8xx is that the command FIFO is quite deep - it's 4 Kbytes. And the GD library will keep on trying to keep that FIFO full.

When you do:

GD.finish();

it forces GD to wait until the 8xx has completely caught up, so there are no frames buffered in the FIFO. GD.get_inputs() has a GD.finish() in it, so it has the same effect.

[leejsmith]

Oct 22, 2019 17:10:04 GMT -8 jamesbowman said:

Right, the thing about the 8xx is that the command FIFO is quite deep - it's 4 Kbytes. And the GD library will keep on trying to keep that FIFO full.

When you do:

GD.finish();

it forces GD to wait until the 8xx has completely caught up, so there are no frames buffered in the FIFO. GD.get_inputs() has a GD.finish() in it, so it has the same effect.

Thanks, that makes sense. Today I am going to make up a PCB on my CNC so I can plug the teensy 3.6, GD 3x and a SNES socket into it instead of the wires.

[leejsmith]

Oct 22, 2019 17:10:04 GMT -8 jamesbowman said:

Right, the thing about the 8xx is that the command FIFO is quite deep - it's 4 Kbytes. And the GD library will keep on trying to keep that FIFO full.

When you do:

GD.finish();

it forces GD to wait until the 8xx has completely caught up, so there are no frames buffered in the FIFO. GD.get_inputs() has a GD.finish() in it, so it has the same effect.

Do you have any examples or guides to sprite collision ? I am looking at how the frogger works and understand most of it, but I can't get two simple sprites to show they have collided.

The manual does not cover this at least that I can find. Only tagging buttons for touch ect.

[jamesbowman]

Yes, frogger is the best example. Collision detection in this hardware is single (x,y) point only. You select the point like this, setting the (x,y) registers:


GD.wr(REG_TAG_X, frogx - 8);
 GD.wr(REG_TAG_Y, frogy);
and then after the swap() and finish() you can read the tag of the last thing drawn that point:

 byte tag = GD.rd(REG_TAG);


[leejsmith]

Oct 24, 2019 6:18:14 GMT -8 jamesbowman said:

Yes, frogger is the best example. Collision detection in this hardware is single (x,y) point only. You select the point like this, setting the (x,y) registers:


GD.wr(REG_TAG_X, frogx - 8);
 GD.wr(REG_TAG_Y, frogy);
and then after the swap() and finish() you can read the tag of the last thing drawn that point:

 byte tag = GD.rd(REG_TAG);


Do I need to set tags before each sprite 

GD.Tag(1); was for the background
GD.Tag(2); was for the moving sprites.

I am not in front of my computer so do not have my code, but I just draw one sprite in tag 1 and then the sprite I move after tag 2 and did the GD.rd(REG_TAG), but it was not changing when they collided. Also what about the GD.TagMask(0); commands, I see that is before and after the frog is drawn on the screen.


edit: I expect it's because I am not doing the swap or finish at the correct place in my code.