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first draft of my oledtest.

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dettus 2022-01-16 23:19:09 +01:00
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LICENSE
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MIT License
MIT No Attribution
Copyright (c) 2022 dettus
Copyright 2022 Thomas Dettbarn (dettus@dettus.net)
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
Permission is hereby granted, free of charge, to any person obtaining a copy of this
software and associated documentation files (the "Software"), to deal in the Software
without restriction, including without limitation the rights to use, copy, modify,
merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so.
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

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README.md
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# oledtest
Waveshare SH1106 on a Jetson Nano
# BACKGROUND
So, I treated myself to a nice little Waveshare OLED 1.3 SH1106 board and tried to get it running
with a BananaPi Zero. (Thus far, I failed.)
The other day, I got my hands on a NVIDIA Jetson Nano, and was able to find a working example. It
was okay, but not of the quality I was expecting. So I decided to come up with my own, and this
is the result.
# COMPILING
Please have a look at the sourcecode. It is imperative that the GPIO numbering from the
(deprecated) sysfs is being reflected in the physicalmapping[] array. Thus, the first time you
try to compile it, it will fail.
Find the #if 0 line which reflects your board, or find the correct sysfs mapping for your board.
Really really sorry, this is what happens when you become a maker.
Once you changed one of the #if 0 to #if 1, you can compile it with
gcc -O3 -o oledtest.app oledtest.c
IF YOU HAVE A NEW BOARD, PLEASE DO NOT HESITATE TO SEND ME THE MAPPING.
dettus@dettus.net, make sure to include "OLEDTEST" somewhere in the subject line.
# RUNNING
Just run ./oledtest.app and watch the display. It should show you two alternating bitmaps.
If it complains about a GPIO pin -1, your sysfs mapping does not work with the OLED hat.
Then you have to do some rewiring. You need to find 7 GPIO pins which are free.

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build.sh 100755
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#!/bin/sh
#MIT No Attribution
#
#Copyright 2022 Thomas Dettbarn (dettus@dettus.net)
#
#Permission is hereby granted, free of charge, to any person obtaining a copy of this
#software and associated documentation files (the "Software"), to deal in the Software
#without restriction, including without limitation the rights to use, copy, modify,
#merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
#permit persons to whom the Software is furnished to do so.
#
#THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
#INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
#PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
#HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
#OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
#SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
gcc -O3 -o oledtest.app oledtest.c

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oledtest.c 100644
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/*
MIT No Attribution
Copyright 2022 Thomas Dettbarn (dettus@dettus.net)
Permission is hereby granted, free of charge, to any person obtaining a copy of this
software and associated documentation files (the "Software"), to deal in the Software
without restriction, including without limitation the rights to use, copy, modify,
merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#include <stdlib.h>
#include <signal.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <fcntl.h>
#define RETVAL_OK 0
#define RETVAL_NOK -1
#define GPIO_INPUT 0
#define GPIO_OUTPUT 1
#define MAXBUFLEN 64
#define DELAY_US(us) usleep((us));
#define DELAY_MS(ms) usleep((ms)*1000);
#define SPI_MODE0 0
#define SPI_MODE1 1
#define SPI_MODE2 2
#define SPI_MODE3 3
#define SPI_LSBFIRST 0
#define SPI_MSBFIRST 1
#define SPI_DELAY //DELAY_US(1)
#define BITMAP_HEIGHT 64
#define BITMAP_WIDTH 128
//// depends on the development board
// the way I understand this is, that the physical pins are mapped into
// the system memory. to accces those, there is some sort of memory
// offset maybe
#if 0
#warning "This mapping is for the Jetson Nano board."
// Jetson Nano
// source: https://maker.pro/nvidia-jetson/tutorial/how-to-use-gpio-pins-on-jetson-nano-developer-kit
const short physicalmapping[41]={
0, // placeholder. there is no PIN0
-1, -1,// PIN1 =3.3V DC, PIN2 =5V DC
-1, -1,
-1, -1,
216, -1, //PIN7 = AUDIO_MCLK
-1, -1,
50, 79, //PIN11=UART_2_RTS,PIN12=I2S_4_CLK
14, -1,
194,232,
-1, 15,
16, -1,
17, 13,
18, 19,
-1, 20,
-1, -1,
149, -1,
200,168,
38, -1,
76, 51,
12, 77,
-1, 78
};
#elif 0
#warning "This mapping is for the Banana Pi board."
// source: https://wiki.fw-web.de/doku.php?id=en:bpi-r64:gpio
const short physicalmapping[41]={
0, // placeholder. there is no PIN0
-1, -1,// PIN1 =3.3V DC, PIN2 =5V DC
56, -1,// 3,4
55, -1,// 5,6
101, 59, //PIN7 = PWM7,8
-1, 60,// 9,10
51, -1, //PIN11=UART_2_RTS,PIN12=I2S_4_CLK
52, -1, //13,14
98, 61, //15,16
-1, 62, //17,18
68, -1, //19,20
69, 63, //21,22
67, 70, //23,24
-1, 66, //25,26
58, 57, //27,28
85, -1, //29,30
82, 64, //31,32
-1, -1, //33,34
-1, 65, //35,36
86, -1, //37,38
-1, -1 //39,40
};
#else
#error "Please have a look at the source code and select one of the mappings from the sysfs numbering to the physical pins"
#endif
// this is the GPIO pinout for the waveshare OLED 1.3 SH1106 hat
#define PIN_CS (physicalmapping[24])
#define PIN_RST (physicalmapping[22])
#define PIN_DC (physicalmapping[18])
#define PIN_BL (physicalmapping[12])
#define PIN_SCLK (physicalmapping[23])
#define PIN_MOSI (physicalmapping[19])
#define PIN_MISO (physicalmapping[21])
int gpio_export(int pin)
{
int fd;
char buffer[MAXBUFLEN];
int len;
fd=open("/sys/class/gpio/export", O_WRONLY);
if (fd<0)
{
fprintf(stderr,"GPIO export for pin %d failed\n",pin);
return RETVAL_NOK;
}
len=snprintf(buffer,MAXBUFLEN,"%d",pin);
write(fd,buffer,len);
close(fd);
return RETVAL_OK;
}
int gpio_unexport(int pin)
{
int fd;
char buffer[MAXBUFLEN];
int len;
fd=open("/sys/class/gpio/unexport", O_WRONLY);
if (fd<0)
{
fprintf(stderr,"GPIO unexport for pin %d failed\n",pin);
return RETVAL_NOK;
}
len=snprintf(buffer,MAXBUFLEN,"%d",pin);
write(fd,buffer,len);
close(fd);
return RETVAL_OK;
}
int gpio_direction(int pin,int direction)
{
int fd;
char buffer[MAXBUFLEN];
snprintf(buffer,MAXBUFLEN,"/sys/class/gpio/gpio%d/direction",pin);
fd=open(buffer,O_WRONLY);
if (fd<0)
{
fprintf(stderr,"GPIO direction for pin %d cannot be set\n",pin);
return RETVAL_NOK;
}
if (direction==GPIO_INPUT)
{
write(fd,"in",2);
} else if (direction==GPIO_OUTPUT) {
write(fd,"out",3);
} else {
fprintf(stderr,"Type error for direction for pin %d (%d unknown)\n",pin,direction);
}
close(fd);
return RETVAL_OK;
}
int gpio_write(int pin,int value)
{
int fd;
char buffer[MAXBUFLEN];
snprintf(buffer,MAXBUFLEN,"/sys/class/gpio/gpio%d/value",pin);
fd=open(buffer,O_WRONLY);
if (fd<0)
{
fprintf(stderr,"Cannot access GPIO pin %d\n",pin);
return RETVAL_NOK;
}
write(fd,value?"1":"0",1);
close(fd);
return RETVAL_OK;
}
int gpio_read(int pin,int* value)
{
int fd;
char buffer[MAXBUFLEN];
int len;
snprintf(buffer,MAXBUFLEN,"/sys/class/gpio/gpio%d/value",pin);
fd=open(buffer,O_WRONLY);
if (fd<0)
{
fprintf(stderr,"Cannot access GPIO pin %d\n",pin);
return RETVAL_NOK;
}
len=read(fd,buffer,3);
if (len<0)
{
fprintf(stderr,"Unable to read from pin %d\n",pin);
close(fd);
return RETVAL_NOK;
}
*value=atoi(buffer);
close(fd);
return RETVAL_OK;
}
int gpio_pins_up()
{
int retval;
retval=RETVAL_OK;
// start with the GPIO configuration
retval|=gpio_export(PIN_RST);
retval|=gpio_export(PIN_DC);
retval|=gpio_export(PIN_BL);
retval|=gpio_export(PIN_CS);
retval|=gpio_direction(PIN_RST, GPIO_OUTPUT);
retval|=gpio_direction(PIN_DC, GPIO_OUTPUT);
retval|=gpio_direction(PIN_BL, GPIO_OUTPUT);
retval|=gpio_direction(PIN_CS, GPIO_OUTPUT);
// continue with the SPI pins
retval|=gpio_export(PIN_SCLK);
retval|=gpio_export(PIN_MOSI);
retval|=gpio_export(PIN_MISO);
retval|=gpio_direction(PIN_SCLK, GPIO_OUTPUT);
retval|=gpio_direction(PIN_MOSI, GPIO_OUTPUT);
retval|=gpio_direction(PIN_MISO, GPIO_INPUT);
return retval;
}
int gpio_pins_down()
{
int retval;
retval=RETVAL_OK;
retval|=gpio_write(PIN_RST,0);
retval|=gpio_write(PIN_DC,0);
retval|=gpio_write(PIN_BL,0);
retval|=gpio_unexport(PIN_RST);
retval|=gpio_unexport(PIN_DC);
retval|=gpio_unexport(PIN_BL);
retval|=gpio_unexport(PIN_CS);
retval|=gpio_write(PIN_SCLK,0);
retval|=gpio_write(PIN_MOSI,0);
retval|=gpio_unexport(PIN_SCLK);
retval|=gpio_unexport(PIN_MOSI);
retval|=gpio_unexport(PIN_MISO);
return retval;
}
void spi_writebyte(unsigned char byte,int mode,int msbfirst)
{
int cpol;
int cpol0;
int cpha;
int bits;
switch (mode)
{
case SPI_MODE0: cpol=0;cpha=0;break;
case SPI_MODE1: cpol=0;cpha=1;break;
case SPI_MODE2: cpol=1;cpha=0;break;
case SPI_MODE3: cpol=1;cpha=1;break;
}
cpol0=cpol;
gpio_write(PIN_SCLK,cpol);
if (!cpha)
{
cpol=1-cpol; // when CPHA=1, the new value is being sampled at the first clock edge
SPI_DELAY;
}
for (bits=0;bits<8;bits++)
{
int bit;
if (msbfirst==SPI_MSBFIRST)
{
bit=(byte>>7)&1;
byte<<=1;
} else {
bit=(byte)&1;
byte>>=1;
}
gpio_write(PIN_MOSI,bit); // set the value
gpio_write(PIN_SCLK,cpol); // 1st clock edge
cpol=1-cpol;
SPI_DELAY;
gpio_write(PIN_SCLK,cpol); // 2nd clock edge
cpol=1-cpol;
SPI_DELAY;
}
gpio_write(PIN_SCLK,cpol0); // make sure that the SPI clk is the same as before
}
void oled_reset()
{
gpio_write(PIN_DC,0);
gpio_write(PIN_RST,1);
DELAY_MS(200);
gpio_write(PIN_RST,0);
DELAY_MS(200);
gpio_write(PIN_RST,1);
DELAY_MS(200);
}
void oled_init()
{
const unsigned char oled_commands[]={
0xae,0x02,0x10,0x40, 0x81,0xa0,0xc0,0xa6, // turn off oled panel, set low column addr, set high column addr, set start line, set contrast control register, set SEG/Column Mapping, Set COM/ROW scan direction, set normal display
0xa8,0x3f,0xd3,0x00, 0xd5,0x80,0xd9,0xf1, // set multiplex ration 1:64, 1/64 duty, set display offset, not offset, set display clock, set divide clock as 100frames/sec, set pre-charge period, set pre-chare as 15 clocks & discarge as 1 clock
0xda,0x12,0xdb,0x40, 0x20,0x02,0xa4,0xa6, // set com pins hardare, ???, set vcomh, set vcom deselect level, set page addr mode, ???, disable entire display on, disable inverse display on,
0xaf // turn on oled panel
};
int i;
gpio_write(PIN_DC,0);
for (i=0;i<sizeof(oled_commands);i++)
{
spi_writebyte(oled_commands[i],SPI_MODE0,SPI_MSBFIRST);
}
}
void oled_draw(unsigned char* bitmap)
{
#define CANVAS_WIDTH 128
#define CANVAS_PAGES 8
unsigned char canvas[CANVAS_WIDTH*CANVAS_PAGES];
int i;
for (i=0;i<CANVAS_WIDTH*CANVAS_PAGES;i++)
{
// each byte in the canvas represents a column of 8 bits from the bitmap
// 0000
// 1111
// 2222
// 3333
// 4444
// ...
int j;
unsigned char byte;
int x,y;
byte=0;
x=i%BITMAP_WIDTH;
y=(i/BITMAP_WIDTH)*8;
for (j=0;j<8;j++)
{
int bit;
bit=bitmap[x+(y+j)*BITMAP_WIDTH]?0x80:0x00;
byte>>=1;
byte|=bit;
}
canvas[i]=byte;
}
for (i=0;i<CANVAS_PAGES;i++)
{
int j;
gpio_write(PIN_DC,0); // write command
spi_writebyte(0xb0+i,SPI_MODE0,SPI_MSBFIRST); // set page address
spi_writebyte(0x02,SPI_MODE0,SPI_MSBFIRST); // set low column address
spi_writebyte(0x10,SPI_MODE0,SPI_MSBFIRST); // set high column address
gpio_write(PIN_DC,1); // write data
for (j=0;j<CANVAS_WIDTH;j++)
{
spi_writebyte(canvas[i*CANVAS_WIDTH+j],SPI_MODE0,SPI_MSBFIRST);
}
}
}
int sh1106_up()
{
int retval;
retval=RETVAL_OK;
retval|=gpio_pins_up();
// spi mode 0
// spi master
// spi clock div 2
// spi msbfirst
// ?? tell the device it should take orders from SPI??
retval|=gpio_write(PIN_BL,1);
retval|=gpio_write(PIN_CS,0);
if (retval==RETVAL_OK)
{
oled_reset();
oled_init();
}
return retval;
}
int sh1106_down()
{
return gpio_pins_down();
}
void graceFulExit(int signal_number)
{
printf("shutting down display...\n");
sh1106_down();
exit(0);
}
int main(int argc,char** argv)
{
unsigned char bitmap[BITMAP_WIDTH*BITMAP_HEIGHT]={0};
unsigned char bitmap2[BITMAP_WIDTH*BITMAP_HEIGHT]={0};
int i;
signal(SIGINT, graceFulExit);
if (sh1106_up())
{
fprintf(stderr,"unable to start up display. sorry");
return 1;
}
for (i=0;i<BITMAP_WIDTH*BITMAP_HEIGHT;i++)
{
if ((i%10)<5) bitmap[i]=1;else bitmap[i]=0;
}
for (i=0;i<BITMAP_HEIGHT;i++)
{
bitmap2[i+i*BITMAP_WIDTH]=1;
}
// draw the two bitmaps, one after the other
for (i=0;i<10;i++)
{
oled_draw(bitmap);
printf("%d\n",i);
oled_draw(bitmap2);
}
printf("press Enter to quit\n");
fgets(bitmap,sizeof(bitmap),stdin);
graceFulExit(0);
return 0;
}