GPIO as Output | Telit Cinterion IoT Developer Community
April 13, 2016 - 3:06pm, 3574 views
For some reason my IO pins which I have set as output using the 'AT^sspi' command are always HIGH when the device boots and only when my programs is running after the boots it sets it back to LOW using the 'AT^ssio'.
I dont want my output pins to be HIGH by default when it boots.
Any help would be apreciated.
Could you please specify which module you are using and is it a terminal version or not?
Generally there are some startup or default pin states which can be later changed by the application but the lines behaviour on start can't be changed.
Hi, Thanks for your reply.
I am using EHSx6 Terminal
Could it be my wiring to th LED?
This is how I have mine connected:
[VCCref,+5v ] --[Resistor]--(LED)----GPIO PIN
If you are using the terminal the module's GPIO lines are connected to the level shifters in terminal. So you need to configure these level shifters as input or output according to the hardware description document for terminal. Have you done this? After this is done you can configure and drive the pins with AT commands.
You have to connect some voltage (you can use +5V from the terminal connector) to VCCref pin. Then, if you have configured the pin as output, you could connect some resistor with LED to that pin and to ground and see the LED flashing while you change the states.
Hi,Yes I have programmed the level shifters by applying the following commands:
1. When the device boots for few seconds all output pins are high which I dont want.
2. For some reason all my commands to swtch then on or of are inverted? I mean if I want to switch a pin to OFF it comes ON and if I want to switch them ON it goes OFF?
The startup behaviour of pins is something that can't be changed.
Some of the pins that you are using can be used by other interfaces also. Please check AT^SCFG? response for the configuration of hardware interfaces.
Please also paste some log how you configure and use GPIO (with commands and answers).