#espidf

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Fixing that ‘Brownout detector was triggered’ error

Although some suggest to switch pff entirely that brownout detector with this line:

WRITE_PERI_REG(RTC_CNTL_BROWN_OUT_REG, 0);

Reality is, - it might be just your USB cable... Get a better cable and you might have your problem fixed. Worked for me.

[skitsanoscom]

Passing servicename as integer to getaddrinfo

The getaddrinfo function provides protocol-independent translation from an ANSI host name to an address.

Given node and service, which identify an Internet host and a service, getaddrinfo() returns one or more addrinfo structures, each of which contains an Internet address that can be specified in a call to bind or connect. The getaddrinfo() function combines the functionality provided by the gethostbyname and getservbyname functions into a single interface, but unlike the latter functions, getaddrinfo() is reentrant and allows programs to eliminate IPv4-versus-IPv6 dependencies.

A service name is a string alias for a port number. For example, “http” is an alias for port 80 defined by the Internet Engineering Task Force (IETF) as the default port used by web servers for the HTTP protocol.

When you running http server on port 3000, for example like in case of Express under Node.js, you will need to pass service name as 3000, but as a string

Below is an example on how to convert port number into a string:

ESP_LOGI(TAG, "... allocated socket"); //get socket service as string from port number size_t length = snprintf(NULL, 0, "%d", params.port); char *port_buf = (char *) malloc(length + 1); sprintf(port_buf, "%d", params.port); ESP_LOGW(TAG, "Will be probing port %s....", port_buf); int err = getaddrinfo(params.server, port_buf, &hints, &res); free(port_buf);

[skitsanoscom]

Reading ADC data on ESP32

Using adc_services in swarmos/ldnode running on ESP32

#include <stdio.h> #include <stdlib.h> #include <string.h> #include "freertos/FreeRTOS.h" #include "freertos/task.h" #include "driver/gpio.h" #include "driver/adc.h" #include "esp_adc_cal.h" #include "esp_log.h" #include "adc_services.h" #define TAG "soil-moisture" #define ADC1_TEST_CHANNEL (ADC1_CHANNEL_7) //pin D35 on ESP32 #define V_REF 1000 // ADC reference voltage void app_main() { ESP_LOGI(TAG, "Loading..."); adc_check_efuse(); esp_err_t status; status = adc2_vref_to_gpio(GPIO_NUM_25); if (status == ESP_OK) { printf("v_ref routed to GPIO\n"); } else { printf("failed to route v_ref\n"); } t_adc_config config = { .vref = V_REF, .atten = ADC_ATTEN_11db, .channel = ADC1_TEST_CHANNEL, .width_bit = ADC_WIDTH_12Bit, .adc_num = ADC_UNIT_1 }; t_adc_config *p = malloc(sizeof(t_adc_config)); memcpy(p, &config, sizeof(t_adc_config)); xTaskCreate(adc_read_task, "ADC read task", 2048, p, 5, NULL); }

Details on ESP-IDF Analog to Digital Convertor (ADC) can be found on Espressif Programming Guide

[skitsanoscom]

Sending data via multiple channels at once

This example demonstrates how to send same data into multiple channels in swarmos/ldnode.

Code uses two channels

ROUTER_CHANNEL_CONSOLE, and

ROUTER_CHANNEL_HTTP

For the ROUTER_CHANNEL_HTTP channel there is additional data sent via Query String.

char *msg = "Hello there"; data_router_send(ROUTER_CHANNEL_CONSOLE, "\n%s\n", msg); t_http_request_parameters parameters = { .protocol = "http", .server = "api.skitsanos.com", .port = 80, .url = "/", .method = HTTP_METHOD_POST, .content_type = "application/json", .query_string = "temp=23&humidity=95", .data = msg }; t_http_request_parameters *p = malloc(sizeof(t_http_request_parameters)); memcpy(p, &parameters, sizeof(t_http_request_parameters)); data_router_send(ROUTER_CHANNEL_HTTP, p);

[skitsanoscom]

Another method on getting embedded content

This time using while loop to go on each char.

EXT_EMBED_FILE(index_html); char *p = (char *) EXT_EMBED_FILE_CONTENT(index_html); while (p != EXT_EMBED_FILE_END(index_html)) putchar(*p++);

[skitsanoscom]

Embedding resources in ESP-IDF

When you want to serve some resources on ESP32 web server, or simply, you need to have some read-only content embedded, instead styoring on SPIFFS or some other filesystem, you can embedd it into your application.

In my case i've created a /data folder where i want to store my index.html file that would be embedded during compilation into my application.

-/data --index.html -/main --app.c --component.mk

Notice component.mk there, it looks like this:

COMPONENT_EMBED_FILES := ../data/index.html

To make it all work, you need to grab embed_file.h

embed_file.h has few macros functions defined:

EXT_EMBED_FILE(name)

EXT_EMBED_FILE_SIZE(name)

EXT_EMBED_FILE_CONTENT(name)

And here is the example on how to use it:

#include <stdio.h> #include "esp_log.h" #define TAG "esp32" #include "../components/utils/embed_file.h" EXT_EMBED_FILE(index_html) void app_main() { size_t len = EXT_EMBED_FILE_SIZE(index_html); uint8_t *content = EXT_EMBED_FILE_CONTENT(index_html); ESP_LOGI(TAG, "index.html size: %d bytes", len); ESP_LOGI(TAG, "index.html content: \n%s", (char *) content); }

[skitsanoscom]

expected string literal before

Programming in C after C# and JavaScript is certainly a challenge, reminds me early 90s with PDS Basic and TurboBasic where you need to implement everything yourself...

Was about to write some piece of code here, but smashed into an error 'expected string literal before' on the following line

extern const uint8_t bin_start[] asm(buf_start);

from this particular code.

#include "esp_log.h" #include "../utils/str_builder.h" #include "../utils/str_replace.h" #define COMPONENT_TAG "erofs" static void erofs_get_tag(char **buf, const char *name, const char *sfx) { str_builder_t *sb = str_builder_create(); str_builder_add_str(sb, "_binary_", 0); //str_builder_add_str(sb, name, 0); char *rs = str_replace((char *) name, ".", "_"); str_builder_add_str(sb, rs, 0); str_builder_add_str(sb, sfx, 0); *buf = str_builder_dump(sb, NULL); str_builder_destroy(sb); free(rs); } void erofs_size(const char *name) { ESP_LOGI(COMPONENT_TAG, "verifying %s", name); char *buf_start; erofs_get_tag(&buf_start, name, "_start"); char *buf_end; erofs_get_start(&buf_end, name, "_end"); ESP_LOGI(COMPONENT_TAG, "%s", buf_start); ESP_LOGI(COMPONENT_TAG, "%s", buf_end); extern const uint8_t bin_start[] asm(buf_start); //... free(buf_start); free(buf_end); }

And here is the surprise, you can't call asm() with varibale name. asm() is a compile-time construct. The argument must be a string literal, and not a variable.

[skitsanoscom]

Syntax example on reading BME680

Below is the syntax example on how to read BME680 sensor data on ESP-IDF:

ESP_LOGI(TAG, "Installing BME680 driver"); bosch_i2c_master_init(I2C_MODE_MASTER, GPIO_NUM_4, GPIO_NUM_5); xTaskCreate(task_bme680_read, "bme680 read", 2048, NULL, 10, NULL);