Function to set DIO2 of SX126x chips to be used as RF antenna switch

[beegee-tokyo]

Add function to set DIO2 of SX126x chips to be used as RF antenna switch.
Based on example design of Semtech and used in many modules.

This breaks the CAD function as DIO2 cannot be used as IRQ output.

Signed-off-by: Bernd Giesecke [email protected]

[beegee-tokyo]

Tested on two modules

• eByte E22-900M which does not use DIO2 as RF antenna switch
• Insight ISP4520 which does use DIO2 as RF antenna switch

TODO
Get CAD function to work again (e.g. by using DIO3 if available).

[jgromes]

Also, I don't think it't a good idea to use DIO3 for CAD timeout. DIO3 must be used on some modules for TCXO control.

If RF control on DIO2 is enabled, CAD should be disabled entirely.

[beegee-tokyo]

Testing the changes right now. Function moved to SX126x.cpp, memory leak removed, simplified, removed unnecessary functions.

Question before I push the changes.

Do you want a new error value for scanChannel() if DIO2 is used for RF antenna switch?

[jgromes]

Since that's quite a unique error, I think a new status code is a good idea. It should have the value -708.

[beegee-tokyo]

/*!
  \brief SX126x scan channel not possible because DIO2 is used as RF antenna switch.
*/
#define ERR_DIO2_UNAVAIL_CAD_FAILED           -708

and

int16_t SX126x::scanChannel() {
  // check active modem
  if(getPacketType() != SX126X_PACKET_TYPE_LORA) {
    return(ERR_WRONG_MODEM);
  }

  if (_dio2RfSwitch) {
    // If DIO2 is used as RF switch this function does not work
    return(ERR_DIO2_UNAVAIL_CAD_FAILED);
  }
...

[beegee-tokyo]

Should be ok now.

Another thing, I get a compile error on ESP8266 module using PlatformIO. I am not compiling for ESP8266 or including ESP8266.h from the lib (but it is included in RadioLib.h)!

Compiling .pioenvs\LoraSender_4520\libeb3\RadioLib-DIO2\RadioLib.cpp.o
Compiling .pioenvs\LoraSender_4520\libeb3\RadioLib-DIO2\modules\CC1101.cpp.o
Compiling .pioenvs\LoraSender_4520\libeb3\RadioLib-DIO2\modules\ESP8266.cpp.o
Compiling .pioenvs\LoraSender_4520\libeb3\RadioLib-DIO2\modules\HC05.cpp.o
lib\RadioLib-DIO2\src\modules\ESP8266.cpp:183:10: error: prototype for 'uint16_t ESP8266::getNumBytes(uint32_t, size_t)' does not match any in class 'ESP8266'
uint16_t ESP8266::getNumBytes(uint32_t timeout, size_t minBytes) {
^~~~~~~
In file included from lib\RadioLib-DIO2\src\modules\ESP8266.cpp:1:0:
lib\RadioLib-DIO2\src\modules\ESP8266.h:55:12: error: candidate is: virtual size_t ESP8266::getNumBytes(uint32_t, size_t)
size_t getNumBytes(uint32_t timeout = 10000, size_t minBytes = 10);
^~~~~~~~~~~
*** [.pioenvs\LoraSender_4520\libeb3\RadioLib-DIO2\modules\ESP8266.cpp.o] Error 1

The cause is that in ESP8266.h the function is declared as

    size_t getNumBytes(uint32_t timeout = 10000, size_t minBytes = 10);

but in ESP8266.cpp the function is set as

uint16_t ESP8266::getNumBytes(uint32_t timeout, size_t minBytes) {

Will include it in this commit.

[jgromes]

I think we're almost done here. Could you also add a new keyword to keywords.txt? Please use tab to separate the keyword and the type (i.e. actual tab, not spaces).

[jgromes]

All looks good now. Thanks!