Hi MartynC, thanks for your reply and the information.
I have read in the page you have posted, that if the ZS040 only accepts AT commands in uppercase. I will test it.
(normally I use lowercase)
But, when I try to pass it to AT Mode with the PIN34, the led always blink fast, never once each 2 seconds.
The datasheet indicates two ways to pass it to AT mode.
How to get to the AT mode.
Step 1: Input low level to PIN34.
Step 2: Supply power to the module.
Step 3: Input high level to the PIN34. Then the module will enter to AT mode. The baud rate is as
same as the communication time, such as 9600 etc.
Step 1: Connect PIN34 to the power supply PIN.
Step 2: Supply power to module (the PIN34 is also supplied with high level since the PIN34 is connected with
power supply PIN). Then the module will enter to AT module. But at this time, the baud
rate is 38400. In this way, user should change the baud rate at the AT mode, if they
forget the communication baud rate.
I have tested both ways but no AT Mode.
Any idea about this ?