SX1272 Sleep problem.

[pbraida]

Hello,

Anyone here use the Semtech SX1272 Lora chip?

We got the SX1272 working, just replacing the MCU of the design. It is transmitting and receiving as expected.
Now we are trying the ST MCU (STM32L083CZT), but we got an issue.
The SX1272 is communicating perfectly over the SPI, we hooked a logic analyzer to check if communication was okay.
However the SX refused to change the value at the mode register (0x01). No matter what we tried to write, then we tried to write another register and the register got 0x00 written to it regardless of what we tried to write.
Then we desoldered and swapped the IC for a fresh one and tested again, this time we got the registers writing properly, but the mode register (0x01) only writes the values 0x80 and 0x00. We can’t set it into standby, transmit or receive.

Is there any known issue that causes this? Like damaged IC, wrong register setup, etc.

Thanks in advance.

Pedro.

[vern]

I had a problem with the SX1276, sounds similar, wrong register content etc.
The problem was that I pulled the reset pin low after a manual reset (high pulse) but you have to leave it open, high Z.
Now it's running perfectly.
I checked the SX1272 datasheet and it also says "high Z after reset".

[pbraida]

I had a problem with the SX1276, sounds similar, wrong register content etc.
The problem was that I pulled the reset pin low after a manual reset (high pulse) but you have to leave it open, high Z.
Now it's running perfectly.
I checked the SX1272 datasheet and it also says "high Z after reset".

Vern thanks, but my reset is working in this maner. I believe the problem is the clock. I am still working on that.
Pedro