customize publish function in mqtt sample

RE: customize publish function in mqtt sample

mschweig — Tue, 11 Jun 2019 10:23:44 GMT

Hi, thanks!

RE: customize publish function in mqtt sample

Linus — Tue, 11 Jun 2019 09:30:56 GMT

Hi!

You are using sprintf() in the wrong way. It doesn't return a string, but the number of characters used in the result. Here's how you should use it:

sprintf(buffer, "%u", val);
data_publish(&client, MQTT_QOS_1_AT_LEAST_ONCE, buffer, 1);

Regards,

Linus

RE: customize publish function in mqtt sample

mschweig — Fri, 07 Jun 2019 09:04:20 GMT

Hi,

yes, ofc I can call this and it is being successfully published, but I would like to call it on a event, for example on button press. Or publish the current button state.

In would have used gpio_pin_read in while (1) and the use the data_publish function, but that does not work.

while (1) {

                u32_t val = 0;
                gpio_pin_read(gpiob, PIN, &val);
                printk("Button: %d\n", val);

                char buffer[2];

                
                data_publish(&client, MQTT_QOS_1_AT_LEAST_ONCE,sprintf(buffer,"%u",val), 1);

Also tried it without conversion to string.

Do you have a better solution how to solve that?

Thanks!

RE: customize publish function in mqtt sample

Hakon — Fri, 07 Jun 2019 08:22:08 GMT

Hey, can't you just call

data_publish(&client, MQTT_QOS_1_AT_LEAST_ONCE, "200,myCustomTemperatureMeasurement,fahrenheit,75.2,F", strlen("200,myCustomTemperatureMeasurement,fahrenheit,75.2,F"));

Just make sure you run it after subscribing.

RE: customize publish function in mqtt sample

mschweig — Mon, 03 Jun 2019 14:52:28 GMT

For example I want to publish that string which can be used with our IoT-Platform:

"200,myCustomTemperatureMeasurement,fahrenheit,75.2,F"