RN4020 not working with Samsung Android 10
I am having a problem using the RN4020 with Samsung devices running Android 10. The same Samsung device running Android 9 works. I don't think it's a problem with Samsung or my code, for reasons described below. I am using MLDP. I recreated this in 1.23 and 1.33 RN4020 firmware.
The symptom is the RN4020 seems to get in a half state where it doesn't think it's connected, but Android does. The connect LED on the RN4020 is not lit, but the 'Connected' state from the 'D' command on the RN4020 says it is connected, the RN4020 is receiving data from the Android, but data sent from the RN4020 is not received by the Android.
The RN4020 does seem to warn me that something bad has happened, because when the Android 10 device connects I get these unitiated messages from the RN4020 and it exists MLDP mode (I have to toggle the MLDP pin to go back into MLDP mode):
Microchip does not document what those values mean. But I usually only seem them when the other device has disconnected from the RN4020.
I was able to recreate this in a native Java Android App that I developed, as well as a Cordova framework Android App that I developed. It's of interest to note that the MLDP Terminal app that Microchip developed doesn't work on my Android 10 Samsung devices (scanning doesn't find any RN4020s) but it does work in Android 9 Samsung devices.
Here is the result of the 'D' command when it has this weird faulty connection to Android 10:
Notice that the 'Connected' says it is connected. Android 10 says it is connected. But the connect LED is not lit. I can receive data from the Android but Android does not receive the data from the RN4020.
Here is the result of the 'D' command when it's connected to Android 9: