esh

General

The embedded shell (esh) is a shell like environment emulated on top of UART. esh can be used to create simple text-based user interfaces (TUI).

Features

• custom commands
• command parameters
• tab autocompletion
• echoing
• command history
• C-like execution environment

Example

#include <semf/communication/esh/shell.h>
#include <semf/hardwareabstraction/stm32f1/stm32f1gpio.h>
#include <semf/hardwareabstraction/stm32f1/stm32f1uart.h>
#include <semf/utils/core/signals/staticslot.h>
#include "main.h"
#include <cstdlib>
 
extern UART_HandleTypeDef huart1;
 
static semf::Stm32F1Gpio led(User_LED_GPIO_Port, User_LED_Pin);
static semf::Stm32F1Uart eshUart(huart1);
 
void ledctl([[maybe_unused]] int argc, char** argv, [[maybe_unused]] semf::esh::Printer& out, int& retCode)
{
    int v = atoi(argv[1]);
    if (v)
        led.set();
    else
        led.reset();
    retCode = 0;
}
 
extern "C" void cppMain()
{
    static semf::StaticSlot<int, char**, semf::esh::Printer&, int&> ledctlCb(ledctl);
 
    static char lineBuffer[32];
    static char historyBuffer[5 * sizeof(lineBuffer)];
    static char* argv[sizeof(lineBuffer) / 2];
    static semf::esh::Shell esh(eshUart, semf::esh::Shell::Config{
                                             lineBuffer,
                                             sizeof(lineBuffer),
                                             argv,
                                             sizeof(lineBuffer) / 2,
                                             historyBuffer,
                                             5,
                                             true,
                                             "> ",
                                         });
    static semf::esh::Command ledctlCmd("ledctl", "help of ledctl", ledctlCb, esh);
 
    esh.start();
    while (true)
        esh.loop();
}

This example is based on a STM32F1 chip and controls the user LED with the command ledctl. The callback function gets passed the typical parameters argc and argv which contain the parameters. The Printer out represents stdout and can be used to write to the user of the esh. The reference retCode is an out parameter for writing the return code to. The esh expects that once the callback has returned, the command execution will be complete.