Request for Additional Method in ESP Modem: Handling Larger AT Command Responses (IDFGH-13338)

[srikanthpalvai]

Is your feature request related to a problem?

When issuing the commands AT+CMGF=0 and AT+CMGL=4, the response results in more data than usual. To handle this, we need an additional method that takes max_len as an argument.

Describe the solution you'd like.

This method allows the user to specify the maximum length of the output buffer, ensuring that larger responses can be handled appropriately.

extern "C" esp_err_t esp_modem_at_raw_ext(esp_modem_dce_t *dce_wrap, const char *cmd, char *p_out, const char *pass, const char *fail, int timeout, size_t max_len)
{
if (dce_wrap == nullptr || dce_wrap->dce == nullptr) {
return ESP_ERR_INVALID_ARG;
}
std::string out;
auto ret = command_response_to_esp_err(dce_wrap->dce->at_raw(cmd, out, pass, fail, timeout));
if ((p_out != NULL) && (!out.empty())) {
strlcpy(p_out, out.c_str(), max_len);
}
return ret;
}

Describe alternatives you've considered.

#define STR_MAX 1024

esp_modem_dce_t *dce_wrap;
char response[ESP_MODEM_C_API_STR_MAX];
esp_err_t ret = esp_modem_at_raw_ext(dce_wrap, "AT+CMGL=4", response, "OK", "ERROR", 1000, STR_MAX );
if (ret == ESP_OK) {
// Process the response
}

Additional context.

No response

[srikanthpalvai]

@david-cermak
Could you please have a look on it.

[david-cermak]

Yes, I'll look into it, planning on some maintenance work and the v1.2 release in about two weeks.
Meantime, we're open for ideas/suggestions and PRs are welcome.

[srikanthpalvai]

Hi @david-cermak

I was not able to create a pull request for esp-modem
but here is the patch file it will help you.
0001-Add-max_len-parameter-to-esp_modem_at_raw_ext-for-bu.patch

[srikanthpalvai]

Hi @david-cermak
I have fixed it with below logic. Added it in the project root CMakeLists.txt

set(ESP_MODEM_C_API_STR_MAX_DEFAULT 512)
target_compile_definitions(__idf_espressif__esp_modem PUBLIC ESP_MODEM_C_API_STR_MAX=${ESP_MODEM_C_API_STR_MAX_DEFAULT})

even though it's better to have specific method to pass the max_length.
where i have provided it the patch file

[david-cermak]

Fixed in #649