276 lines
10 KiB
C
276 lines
10 KiB
C
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/* SPI Master example
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This example code is in the Public Domain (or CC0 licensed, at your option.)
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Unless required by applicable law or agreed to in writing, this
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software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
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CONDITIONS OF ANY KIND, either express or implied.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "freertos/FreeRTOS.h"
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#include "freertos/task.h"
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#include "esp_system.h"
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#include "driver/spi_master.h"
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#include "soc/gpio_struct.h"
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#include "driver/gpio.h"
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/*
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This code displays some fancy graphics on the ILI9341-based 320x240 LCD on an ESP-WROVER_KIT board.
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It is not very fast, even when the SPI transfer itself happens at 8MHz and with DMA, because
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the rest of the code is not very optimized. Especially calculating the image line-by-line
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is inefficient; it would be quicker to send an entire screenful at once. This example does, however,
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demonstrate the use of both spi_device_transmit as well as spi_device_queue_trans/spi_device_get_trans_result
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as well as pre-transmit callbacks.
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Some info about the ILI9341: It has an C/D line, which is connected to a GPIO here. It expects this
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line to be low for a command and high for data. We use a pre-transmit callback here to control that
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line: every transaction has as the user-definable argument the needed state of the D/C line and just
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before the transaction is sent, the callback will set this line to the correct state.
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*/
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#define PIN_NUM_MISO 25
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#define PIN_NUM_MOSI 23
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#define PIN_NUM_CLK 19
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#define PIN_NUM_CS 22
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#define PIN_NUM_DC 21
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#define PIN_NUM_RST 18
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#define PIN_NUM_BCKL 5
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/*
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The ILI9341 needs a bunch of command/argument values to be initialized. They are stored in this struct.
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*/
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typedef struct {
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uint8_t cmd;
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uint8_t data[16];
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uint8_t databytes; //No of data in data; bit 7 = delay after set; 0xFF = end of cmds.
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} ili_init_cmd_t;
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static const ili_init_cmd_t ili_init_cmds[]={
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{0xCF, {0x00, 0x83, 0X30}, 3},
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{0xED, {0x64, 0x03, 0X12, 0X81}, 4},
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{0xE8, {0x85, 0x01, 0x79}, 3},
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{0xCB, {0x39, 0x2C, 0x00, 0x34, 0x02}, 5},
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{0xF7, {0x20}, 1},
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{0xEA, {0x00, 0x00}, 2},
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{0xC0, {0x26}, 1},
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{0xC1, {0x11}, 1},
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{0xC5, {0x35, 0x3E}, 2},
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{0xC7, {0xBE}, 1},
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{0x36, {0x28}, 1},
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{0x3A, {0x55}, 1},
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{0xB1, {0x00, 0x1B}, 2},
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{0xF2, {0x08}, 1},
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{0x26, {0x01}, 1},
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{0xE0, {0x1F, 0x1A, 0x18, 0x0A, 0x0F, 0x06, 0x45, 0X87, 0x32, 0x0A, 0x07, 0x02, 0x07, 0x05, 0x00}, 15},
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{0XE1, {0x00, 0x25, 0x27, 0x05, 0x10, 0x09, 0x3A, 0x78, 0x4D, 0x05, 0x18, 0x0D, 0x38, 0x3A, 0x1F}, 15},
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{0x2A, {0x00, 0x00, 0x00, 0xEF}, 4},
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{0x2B, {0x00, 0x00, 0x01, 0x3f}, 4},
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{0x2C, {0}, 0},
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{0xB7, {0x07}, 1},
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{0xB6, {0x0A, 0x82, 0x27, 0x00}, 4},
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{0x11, {0}, 0x80},
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{0x29, {0}, 0x80},
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{0, {0}, 0xff},
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};
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//Send a command to the ILI9341. Uses spi_device_transmit, which waits until the transfer is complete.
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void ili_cmd(spi_device_handle_t spi, const uint8_t cmd)
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{
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esp_err_t ret;
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spi_transaction_t t;
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memset(&t, 0, sizeof(t)); //Zero out the transaction
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t.length=8; //Command is 8 bits
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t.tx_buffer=&cmd; //The data is the cmd itself
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t.user=(void*)0; //D/C needs to be set to 0
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ret=spi_device_transmit(spi, &t); //Transmit!
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assert(ret==ESP_OK); //Should have had no issues.
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}
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//Send data to the ILI9341. Uses spi_device_transmit, which waits until the transfer is complete.
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void ili_data(spi_device_handle_t spi, const uint8_t *data, int len)
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{
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esp_err_t ret;
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spi_transaction_t t;
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if (len==0) return; //no need to send anything
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memset(&t, 0, sizeof(t)); //Zero out the transaction
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t.length=len*8; //Len is in bytes, transaction length is in bits.
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t.tx_buffer=data; //Data
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t.user=(void*)1; //D/C needs to be set to 1
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ret=spi_device_transmit(spi, &t); //Transmit!
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assert(ret==ESP_OK); //Should have had no issues.
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}
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//This function is called (in irq context!) just before a transmission starts. It will
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//set the D/C line to the value indicated in the user field.
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void ili_spi_pre_transfer_callback(spi_transaction_t *t)
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{
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int dc=(int)t->user;
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gpio_set_level(PIN_NUM_DC, dc);
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}
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//Initialize the display
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void ili_init(spi_device_handle_t spi)
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{
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int cmd=0;
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//Initialize non-SPI GPIOs
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gpio_set_direction(PIN_NUM_DC, GPIO_MODE_OUTPUT);
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gpio_set_direction(PIN_NUM_RST, GPIO_MODE_OUTPUT);
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gpio_set_direction(PIN_NUM_BCKL, GPIO_MODE_OUTPUT);
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//Reset the display
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gpio_set_level(PIN_NUM_RST, 0);
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vTaskDelay(100 / portTICK_RATE_MS);
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gpio_set_level(PIN_NUM_RST, 1);
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vTaskDelay(100 / portTICK_RATE_MS);
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//Send all the commands
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while (ili_init_cmds[cmd].databytes!=0xff) {
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ili_cmd(spi, ili_init_cmds[cmd].cmd);
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ili_data(spi, ili_init_cmds[cmd].data, ili_init_cmds[cmd].databytes&0x1F);
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if (ili_init_cmds[cmd].databytes&0x80) {
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vTaskDelay(100 / portTICK_RATE_MS);
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}
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cmd++;
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}
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///Enable backlight
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gpio_set_level(PIN_NUM_BCKL, 0);
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}
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//To send a line we have to send a command, 2 data bytes, another command, 2 more data bytes and another command
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//before sending the line data itself; a total of 6 transactions. (We can't put all of this in just one transaction
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//because the D/C line needs to be toggled in the middle.)
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//This routine queues these commands up so they get sent as quickly as possible.
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void send_line(spi_device_handle_t spi, int ypos, uint16_t *line)
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{
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esp_err_t ret;
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int x;
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//Transaction descriptors. Declared static so they're not allocated on the stack; we need this memory even when this
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//function is finished because the SPI driver needs access to it even while we're already calculating the next line.
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static spi_transaction_t trans[6];
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//In theory, it's better to initialize trans and data only once and hang on to the initialized
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//variables. We allocate them on the stack, so we need to re-init them each call.
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for (x=0; x<6; x++) {
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memset(&trans[x], 0, sizeof(spi_transaction_t));
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if ((x&1)==0) {
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//Even transfers are commands
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trans[x].length=8;
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trans[x].user=(void*)0;
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} else {
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//Odd transfers are data
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trans[x].length=8*4;
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trans[x].user=(void*)1;
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}
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trans[x].flags=SPI_USE_TXDATA;
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}
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trans[0].tx_data[0]=0x2A; //Column Address Set
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trans[1].tx_data[0]=0; //Start Col High
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trans[1].tx_data[1]=0; //Start Col Low
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trans[1].tx_data[2]=(320)>>8; //End Col High
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trans[1].tx_data[3]=(320)&0xff; //End Col Low
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trans[2].tx_data[0]=0x2B; //Page address set
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trans[3].tx_data[0]=ypos>>8; //Start page high
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trans[3].tx_data[1]=ypos&0xff; //start page low
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trans[3].tx_data[2]=(ypos+1)>>8; //end page high
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trans[3].tx_data[3]=(ypos+1)&0xff; //end page low
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trans[4].tx_data[0]=0x2C; //memory write
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trans[5].tx_buffer=line; //finally send the line data
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trans[5].length=320*2*8; //Data length, in bits
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trans[5].flags=0; //undo SPI_USE_TXDATA flag
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//Queue all transactions.
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for (x=0; x<6; x++) {
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ret=spi_device_queue_trans(spi, &trans[x], portMAX_DELAY);
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assert(ret==ESP_OK);
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}
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//When we are here, the SPI driver is busy (in the background) getting the transactions sent. That happens
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//mostly using DMA, so the CPU doesn't have much to do here. We're not going to wait for the transaction to
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//finish because we may as well spend the time calculating the next line. When that is done, we can call
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//send_line_finish, which will wait for the transfers to be done and check their status.
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}
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void send_line_finish(spi_device_handle_t spi)
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{
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spi_transaction_t *rtrans;
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esp_err_t ret;
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//Wait for all 6 transactions to be done and get back the results.
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for (int x=0; x<6; x++) {
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ret=spi_device_get_trans_result(spi, &rtrans, portMAX_DELAY);
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assert(ret==ESP_OK);
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//We could inspect rtrans now if we received any info back. The LCD is treated as write-only, though.
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}
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}
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//Simple routine to generate some patterns and send them to the LCD. Don't expect anything too
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//impressive. Because the SPI driver handles transactions in the background, we can calculate the next line
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//while the previous one is being sent.
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void display_pretty_colors(spi_device_handle_t spi)
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{
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uint16_t line[2][320];
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int x, y, frame=0;
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//Indexes of the line currently being sent to the LCD and the line we're calculating.
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int sending_line=-1;
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int calc_line=0;
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while(1) {
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frame++;
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for (y=0; y<240; y++) {
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//Calculate a line.
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for (x=0; x<320; x++) {
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line[calc_line][x]=((x<<3)^(y<<3)^(frame+x*y));
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}
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//Finish up the sending process of the previous line, if any
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if (sending_line!=-1) send_line_finish(spi);
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//Swap sending_line and calc_line
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sending_line=calc_line;
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calc_line=(calc_line==1)?0:1;
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//Send the line we currently calculated.
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send_line(spi, y, line[sending_line]);
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//The line is queued up for sending now; the actual sending happens in the
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//background. We can go on to calculate the next line as long as we do not
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//touch line[sending_line]; the SPI sending process is still reading from that.
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}
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}
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}
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void app_main()
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{
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esp_err_t ret;
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spi_device_handle_t spi;
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spi_bus_config_t buscfg={
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.spiq_io_num=PIN_NUM_MISO,
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.spid_io_num=PIN_NUM_MOSI,
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.spiclk_io_num=PIN_NUM_CLK,
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.spiwp_io_num=-1,
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.spihd_io_num=-1
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};
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spi_device_interface_config_t devcfg={
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.clock_speed_hz=10000000, //Clock out at 10 MHz
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.mode=0, //SPI mode 0
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.spics_io_num=PIN_NUM_CS, //CS pin
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.queue_size=7, //We want to be able to queue 7 transactions at a time
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.pre_cb=ili_spi_pre_transfer_callback, //Specify pre-transfer callback to handle D/C line
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};
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//Initialize the SPI bus
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ret=spi_bus_initialize(HSPI_HOST, &buscfg, 1);
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assert(ret==ESP_OK);
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//Attach the LCD to the SPI bus
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ret=spi_bus_add_device(HSPI_HOST, &devcfg, &spi);
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assert(ret==ESP_OK);
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//Initialize the LCD
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ili_init(spi);
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//Go do nice stuff.
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display_pretty_colors(spi);
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}
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