EHS6 - Switch ASC0 and ASC1 to GPIO usage on the fly | Telit Cinterion IoT Developer Community
March 1, 2016 - 6:59pm, 2521 views
Hi all,
It is mandatory in my project to keep the TX lines (from ASC0 and ASC1) in low level (0V) for some period of time. It is not possible to write 0x00 byte in the line because the serial Start bit can disturb the device that is connected to this line. So I have to change the pins to normal GPIO usage. I know how to do it for ASC1 (changing serial interface allocation at^scfg="Serial/Interface/Allocation") , but I am not sure if it is possible to do it for ASC0. Could you confirm to me, please?
Even for ASC1 that I am sure how to change it, I would like to know if it is possible to do it without restarting the module?
I am using EHS6 module REVISION 03.001.
Thanks and best regards,
Cassio
Hello,
The purpose of "Serial/Interface/Allocation" setting is more the allocation the functions of the serial interfaces then enabling/disabling them and the setting is effective after restart.
Some of the lines of ASC0 and ASC1 are common with GPIO but TX of ASC0 is probably not one of them.
You can use AT^SPOW command to manage the sleep **** of serial interfaces or to disable them.
But I'm not sure if it is possible to avoid any short state change on the lines during the module start. You should measure it to be sure.
Regards,
Bartłomiej
Hi Bartłomiej,
Thank you for the quick reply.
I have disabled the serial interfaces using at^spow=0,0,0. The serial interfaces stops to work, but the TX lines are on high state. It is not possible to change ASC0's pins to GPIO because it is reserved. Do you have any other idea how could I keep the TX lines on low level state?
Best regards,
Cassio
Hello,
Some pins of ASC0 interface are common with GPIO and other interfaces. So if used by some other interface these lines are marked as reserved. But the TX line is not common with any GPIO.
Here's the picture from hardware description document that shows the startup behaviour of the asynchronous serial interface ASC0. The TX and RX are high. So it doesn't seem to be possible to get them low during startup.
Regards,
Bartłomiej