Examples/spi_master: spiffier graphics

examples/peripherals/spi_master/main/Kconfig.projbuild

@@ -14,4 +14,13 @@ config LCD_TYPE_ILI9341
 	bool "ILI9341 (WROVER Kit v1 or DevKitJ v1)"
 endchoice
 
+config LCD_OVERCLOCK
+	bool
+	prompt "Run LCD at higher clock speed than allowed"
+	default "n"
+	help
+		The ILI9341 and ST7789 specify that the maximum clock speed for the SPI interface is 10MHz. However,
+		in practice the driver chips work fine with a higher clock rate, and using that gives a better framerate.
+		Select this to try using the out-of-spec clock rate.
+
 endmenu

examples/peripherals/spi_master/main/component.mk

@@ -3,3 +3,6 @@
 #
 # (Uses default behaviour of compiling all source files in directory, adding 'include' to include path.)
 
+
+#Compile image file into the resulting firmware binary
+COMPONENT_EMBED_FILES := image.jpg

examples/peripherals/spi_master/main/decode_image.c

@@ -0,0 +1,153 @@
+/* SPI Master example: jpeg decoder.
+
+   This example code is in the Public Domain (or CC0 licensed, at your option.)
+
+   Unless required by applicable law or agreed to in writing, this
+   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+   CONDITIONS OF ANY KIND, either express or implied.
+*/
+
+
+/*
+The image used for the effect on the LCD in the SPI master example is stored in flash 
+as a jpeg file. This file contains the decode_image routine, which uses the tiny JPEG 
+decoder library in ROM to decode this JPEG into a format that can be sent to the display.
+
+Keep in mind that the decoder library cannot handle progressive files (will give 
+``Image decoder: jd_prepare failed (8)`` as an error) so make sure to save in the correct
+format if you want to use a different image file.
+*/
+
+
+#include "decode_image.h"
+#include "rom/tjpgd.h"
+#include "esp_log.h"
+#include <string.h>
+
+//Reference the binary-included jpeg file
+extern const uint8_t image_jpg_start[]   asm("_binary_image_jpg_start");
+extern const uint8_t image_jpg_end[]     asm("_binary_image_jpg_end");
+//Define the height and width of the jpeg file. Make sure this matches the actual jpeg
+//dimensions.
+#define IMAGE_W 336
+#define IMAGE_H 256
+
+
+const char *TAG="ImageDec";
+
+
+//Data that is passed from the decoder function to the infunc/outfunc functions.
+typedef struct {
+    const unsigned char *inData;	//Pointer to jpeg data
+    int inPos;						//Current position in jpeg data
+    uint16_t **outData;				//Array of IMAGE_H pointers to arrays of IMAGE_W 16-bit pixel values
+    int outW;						//Width of the resulting file
+    int outH;						//Height of the resulting file
+} JpegDev;
+
+
+//Input function for jpeg decoder. Just returns bytes from the inData field of the JpegDev structure.
+static UINT infunc(JDEC *decoder, BYTE *buf, UINT len) 
+{
+    //Read bytes from input file
+    JpegDev *jd=(JpegDev*)decoder->device;
+    if (buf!=NULL) memcpy(buf, jd->inData+jd->inPos, len);
+    jd->inPos+=len;
+    return len;
+}
+
+//Output function. Re-encodes the RGB888 data from the decoder as big-endian RGB565 and
+//stores it in the outData array of the JpegDev structure.
+static UINT outfunc(JDEC *decoder, void *bitmap, JRECT *rect) 
+{
+    JpegDev *jd=(JpegDev*)decoder->device;
+    uint8_t *in=(uint8_t*)bitmap;
+    for (int y=rect->top; y<=rect->bottom; y++) {
+        for (int x=rect->left; x<=rect->right; x++) {
+            //We need to convert the 3 bytes in `in` to a rgb565 value.
+            uint16_t v=0;
+            v|=((in[0]>>3)<<11);
+            v|=((in[1]>>2)<<5);
+            v|=((in[2]>>3)<<0);
+            //The LCD wants the 16-bit value in big-endian, so swap bytes
+            v=(v>>8)|(v<<8);
+            jd->outData[y][x]=v;
+            in+=3;
+        }
+    }
+    return 1;
+}
+
+//Size of the work space for the jpeg decoder.
+#define WORKSZ 3100
+
+//Decode the embedded image into pixel lines that can be used with the rest of the logic.
+esp_err_t decode_image(uint16_t ***pixels) 
+{
+    char *work=NULL;
+    int r;
+    JDEC decoder;
+    JpegDev jd;
+    *pixels=NULL;
+    esp_err_t ret=ESP_OK;
+
+
+    //Alocate pixel memory. Each line is an array of IMAGE_W 16-bit pixels; the `*pixels` array itself contains pointers to these lines.
+    *pixels=calloc(IMAGE_H, sizeof(uint16_t*));
+    if (*pixels==NULL) {
+        ESP_LOGE(TAG, "Error allocating memory for lines");
+        ret=ESP_ERR_NO_MEM;
+        goto err;
+    }
+    for (int i=0; i<IMAGE_H; i++) {
+        (*pixels)[i]=malloc(IMAGE_W*sizeof(uint16_t));
+        if ((*pixels)[i]==NULL) {
+            ESP_LOGE(TAG, "Error allocating memory for line %d", i);
+            ret=ESP_ERR_NO_MEM;
+            goto err;
+        }
+    }
+
+    //Allocate the work space for the jpeg decoder.
+    work=calloc(WORKSZ, 1);
+    if (work==NULL) {
+        ESP_LOGE(TAG, "Cannot allocate workspace");
+        ret=ESP_ERR_NO_MEM;
+        goto err;
+    }
+
+    //Populate fields of the JpegDev struct.
+    jd.inData=image_jpg_start;
+    jd.inPos=0;
+    jd.outData=*pixels;
+    jd.outW=IMAGE_W;
+    jd.outH=IMAGE_H;
+    
+    //Prepare and decode the jpeg.
+    r=jd_prepare(&decoder, infunc, work, WORKSZ, (void*)&jd);
+    if (r!=JDR_OK) {
+        ESP_LOGE(TAG, "Image decoder: jd_prepare failed (%d)", r);
+        ret=ESP_ERR_NOT_SUPPORTED;
+        goto err;
+    }
+    r=jd_decomp(&decoder, outfunc, 0);
+    if (r!=JDR_OK) {
+        ESP_LOGE(TAG, "Image decoder: jd_decode failed (%d)", r);
+        ret=ESP_ERR_NOT_SUPPORTED;
+        goto err;
+    }
+    
+    //All done! Free the work area (as we don't need it anymore) and return victoriously.
+    free(work);
+    return ret;
+err:
+    //Something went wrong! Exit cleanly, de-allocating everything we allocated.
+    if (*pixels!=NULL) {
+        for (int i=0; i<IMAGE_H; i++) {
+            free((*pixels)[i]);
+        }
+        free(*pixels);
+    }
+    free(work);
+    return ret;
+}

examples/peripherals/spi_master/main/decode_image.h

@@ -0,0 +1,14 @@
+#pragma once
+#include <stdint.h>
+#include "esp_err.h"
+
+/**
+ * @brief Decode the jpeg ``image.jpg`` embedded into the program file into pixel data.
+ *
+ * @param pixels A pointer to a pointer for an array of rows, which themselves are an array of pixels.
+ *        Effectively, you can get the pixel data by doing ``decode_image(&myPixels); pixelval=myPixels[ypos][xpos];``
+ * @return - ESP_ERR_NOT_SUPPORTED if image is malformed or a progressive jpeg file
+ *         - ESP_ERR_NO_MEM if out of memory
+ *         - ESP_OK on succesful decode
+ */
+esp_err_t decode_image(uint16_t ***pixels);

examples/peripherals/spi_master/main/pretty_effect.c

@@ -0,0 +1,61 @@
+/*
+   This code generates an effect that should pass the 'fancy graphics' qualification
+   as set in the comment in the spi_master code.
+
+   This example code is in the Public Domain (or CC0 licensed, at your option.)
+
+   Unless required by applicable law or agreed to in writing, this
+   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+   CONDITIONS OF ANY KIND, either express or implied.
+*/
+
+#include <math.h>
+#include "pretty_effect.h"
+#include "decode_image.h"
+
+uint16_t **pixels;
+
+//Grab a rgb16 pixel from the esp32_tiles image
+static inline uint16_t get_bgnd_pixel(int x, int y)
+{
+    //Image has an 8x8 pixel margin, so we can also resolve e.g. [-3, 243]
+    x+=8;
+    y+=8;
+    return pixels[y][x];
+}
+
+
+//This variable is used to detect the next frame.
+static int prev_frame=-1;
+
+//Instead of calculating the offsets for each pixel we grab, we pre-calculate the valueswhenever a frame changes, then re-use
+//these as we go through all the pixels in the frame. This is much, much faster.
+static int8_t xofs[320], yofs[240];
+static int8_t xcomp[320], ycomp[240];
+
+//Calculate the pixel data for a set of lines (with implied line size of 320). Pixels go in dest, line is the Y-coordinate of the
+//first line to be calculated, linect is the amount of lines to calculate. Frame increases by one every time the entire image
+//is displayed; this is used to go to the next frame of animation.
+void pretty_effect_calc_lines(uint16_t *dest, int line, int frame, int linect)
+{
+    if (frame!=prev_frame) {
+        //We need to calculate a new set of offset coefficients. Take some random sines as offsets to make everything
+        //look pretty and fluid-y.
+        for (int x=0; x<320; x++) xofs[x]=sin(frame*0.15+x*0.06)*4;
+        for (int y=0; y<240; y++) yofs[y]=sin(frame*0.1+y*0.05)*4;
+        for (int x=0; x<320; x++) xcomp[x]=sin(frame*0.11+x*0.12)*4;
+        for (int y=0; y<240; y++) ycomp[y]=sin(frame*0.07+y*0.15)*4;
+        prev_frame=frame;
+    }
+    for (int y=line; y<line+linect; y++) {
+        for (int x=0; x<320; x++) {
+            *dest++=get_bgnd_pixel(x+yofs[y]+xcomp[x], y+xofs[x]+ycomp[y]);
+        }
+    }
+}
+
+
+esp_err_t pretty_effect_init() 
+{
+    return decode_image(&pixels);
+}

examples/peripherals/spi_master/main/pretty_effect.h

@@ -0,0 +1,22 @@
+#pragma once
+#include <stdint.h>
+#include "esp_err.h"
+
+
+/**
+ * @brief Calculate the effect for a bunch of lines.
+ *
+ * @param dest Destination for the pixels. Assumed to be LINECT * 320 16-bit pixel values.
+ * @param line Starting line of the chunk of lines.
+ * @param frame Current frame, used for animation
+ * @param linect Amount of lines to calculate
+ */
+void pretty_effect_calc_lines(uint16_t *dest, int line, int frame, int linect);
+
+
+/**
+ * @brief Initialize the effect
+ *
+ * @return ESP_OK on success, an error from the jpeg decoder otherwise.
+ */
+esp_err_t pretty_effect_init();

examples/peripherals/spi_master/main/spi_master_example_main.c

@@ -16,14 +16,12 @@
 #include "soc/gpio_struct.h"
 #include "driver/gpio.h"
 
+#include "pretty_effect.h"
 
 /*
  This code displays some fancy graphics on the 320x240 LCD on an ESP-WROVER_KIT board.
- It is not very fast, even when the SPI transfer itself happens at 8MHz and with DMA, because
- the rest of the code is not very optimized. Especially calculating the image line-by-line
- is inefficient; it would be quicker to send an entire screenful at once. This example does, however,
- demonstrate the use of both spi_device_transmit as well as spi_device_queue_trans/spi_device_get_trans_result
- as well as pre-transmit callbacks.
+ This example demonstrates the use of both spi_device_transmit as well as 
+ spi_device_queue_trans/spi_device_get_trans_result and pre-transmit callbacks.
 
  Some info about the ILI9341/ST7789V: It has an C/D line, which is connected to a GPIO here. It expects this
  line to be low for a command and high for data. We use a pre-transmit callback here to control that
@@ -40,6 +38,9 @@
 #define PIN_NUM_RST  18
 #define PIN_NUM_BCKL 5
 
+//To speed up transfers, every SPI transfer sends a bunch of lines. This define specifies how many. More means more memory use, 
+//but less overhead for setting up / finishing transfers. Make sure 240 is dividable by this.
+#define PARALLEL_LINES 16
 
 /*
  The LCD needs a bunch of command/argument values to be initialized. They are stored in this struct.
@@ -182,11 +183,11 @@ void lcd_init(spi_device_handle_t spi)
     if ( lcd_id == 0 ) {
         //zero, ili
         lcd_detected_type = LCD_TYPE_ILI;
-        printf("ILI9341 detected...\n");   
+        printf("ILI9341 detected.\n");
     } else {
         // none-zero, ST
         lcd_detected_type = LCD_TYPE_ST;
-        printf("ST7789V detected...\n");
+        printf("ST7789V detected.\n");
     }
 
 #ifdef CONFIG_LCD_TYPE_AUTO
@@ -197,12 +198,12 @@ void lcd_init(spi_device_handle_t spi)
 #elif defined( CONFIG_LCD_TYPE_ILI9341 )
     printf("kconfig: force CONFIG_LCD_TYPE_ILI9341.\n");
     lcd_type = LCD_TYPE_ILI;
-#endif   
+#endif
     if ( lcd_type == LCD_TYPE_ST ) {
         printf("LCD ST7789V initialization.\n");
         lcd_init_cmds = st_init_cmds;
     } else {
-        printf("LCD ILI9341 initialization.\n");   
+        printf("LCD ILI9341 initialization.\n");
         lcd_init_cmds = ili_init_cmds;
     }
 
@@ -221,11 +222,11 @@ void lcd_init(spi_device_handle_t spi)
 }
 
 
-//To send a line we have to send a command, 2 data bytes, another command, 2 more data bytes and another command
+//To send a set of lines we have to send a command, 2 data bytes, another command, 2 more data bytes and another command
 //before sending the line data itself; a total of 6 transactions. (We can't put all of this in just one transaction
 //because the D/C line needs to be toggled in the middle.)
 //This routine queues these commands up so they get sent as quickly as possible.
-static void send_line(spi_device_handle_t spi, int ypos, uint16_t *line) 
+static void send_lines(spi_device_handle_t spi, int ypos, uint16_t *linedata) 
 {
     esp_err_t ret;
     int x;
@@ -256,11 +257,11 @@ static void send_line(spi_device_handle_t spi, int ypos, uint16_t *line)
     trans[2].tx_data[0]=0x2B;           //Page address set
     trans[3].tx_data[0]=ypos>>8;        //Start page high
     trans[3].tx_data[1]=ypos&0xff;      //start page low
-    trans[3].tx_data[2]=(ypos+1)>>8;    //end page high
-    trans[3].tx_data[3]=(ypos+1)&0xff;  //end page low
+    trans[3].tx_data[2]=(ypos+PARALLEL_LINES)>>8;    //end page high
+    trans[3].tx_data[3]=(ypos+PARALLEL_LINES)&0xff;  //end page low
     trans[4].tx_data[0]=0x2C;           //memory write
-    trans[5].tx_buffer=line;            //finally send the line data
-    trans[5].length=320*2*8;            //Data length, in bits
+    trans[5].tx_buffer=linedata;        //finally send the line data
+    trans[5].length=320*2*8*PARALLEL_LINES;          //Data length, in bits
     trans[5].flags=0; //undo SPI_TRANS_USE_TXDATA flag
 
     //Queue all transactions.
@@ -294,28 +295,31 @@ static void send_line_finish(spi_device_handle_t spi)
 //while the previous one is being sent.
 static void display_pretty_colors(spi_device_handle_t spi) 
 {
-    uint16_t line[2][320];
-    int x, y, frame=0;
+    uint16_t *lines[2];
+    //Allocate memory for the pixel buffers
+    for (int i=0; i<2; i++) {
+        lines[i]=heap_caps_malloc(320*PARALLEL_LINES*sizeof(uint16_t), MALLOC_CAP_DMA);
+        assert(lines[i]!=NULL);
+    }
+    int frame=0;
     //Indexes of the line currently being sent to the LCD and the line we're calculating.
     int sending_line=-1;
     int calc_line=0;
     
     while(1) {
         frame++;
-        for (y=0; y<240; y++) {
+        for (int y=0; y<240; y+=PARALLEL_LINES) {
             //Calculate a line.
-            for (x=0; x<320; x++) {
-                line[calc_line][x]=((x<<3)^(y<<3)^(frame+x*y));
-            }
+            pretty_effect_calc_lines(lines[calc_line], y, frame, PARALLEL_LINES);
             //Finish up the sending process of the previous line, if any
             if (sending_line!=-1) send_line_finish(spi);
             //Swap sending_line and calc_line
             sending_line=calc_line;
             calc_line=(calc_line==1)?0:1;
             //Send the line we currently calculated.
-            send_line(spi, y, line[sending_line]);
-            //The line is queued up for sending now; the actual sending happens in the
-            //background. We can go on to calculate the next line as long as we do not
+            send_lines(spi, y, lines[sending_line]);
+            //The line set is queued up for sending now; the actual sending happens in the
+            //background. We can go on to calculate the next line set as long as we do not
             //touch line[sending_line]; the SPI sending process is still reading from that.
         }
     }
@@ -330,10 +334,15 @@ void app_main()
         .mosi_io_num=PIN_NUM_MOSI,
         .sclk_io_num=PIN_NUM_CLK,
         .quadwp_io_num=-1,
-        .quadhd_io_num=-1
+        .quadhd_io_num=-1,
+        .max_transfer_sz=PARALLEL_LINES*320*2+8
     };
     spi_device_interface_config_t devcfg={
-        .clock_speed_hz=10*1000*1000,               //Clock out at 10 MHz
+#ifdef CONFIG_LCD_OVERCLOCK
+        .clock_speed_hz=26*1000*1000,           //Clock out at 26 MHz
+#else
+        .clock_speed_hz=10*1000*1000,           //Clock out at 10 MHz
+#endif
         .mode=0,                                //SPI mode 0
         .spics_io_num=PIN_NUM_CS,               //CS pin
         .queue_size=7,                          //We want to be able to queue 7 transactions at a time
@@ -341,12 +350,16 @@ void app_main()
     };
     //Initialize the SPI bus
     ret=spi_bus_initialize(HSPI_HOST, &buscfg, 1);
-    assert(ret==ESP_OK);
+    ESP_ERROR_CHECK(ret);
     //Attach the LCD to the SPI bus
     ret=spi_bus_add_device(HSPI_HOST, &devcfg, &spi);
-    assert(ret==ESP_OK);
+    ESP_ERROR_CHECK(ret);
     //Initialize the LCD
     lcd_init(spi);
+    //Initialize the effect displayed
+    ret=pretty_effect_init();
+    ESP_ERROR_CHECK(ret);
+
     //Go do nice stuff.
     display_pretty_colors(spi);
 }