updated AB03 preamble lenth selection

Author: Heltec-Aaron-Lee

platform.txt

@@ -59,7 +59,7 @@ compiler.as.cmd.asr6601=arm-none-eabi-as
 compiler.ar.cmd.asr6601=arm-none-eabi-ar
 compiler.objcopy.cmd.asr6601=arm-none-eabi-objcopy
 compiler.size.cmd.asr6601=arm-none-eabi-size
-compiler.cpreprocessor.flags.asr6601=-D{build.band}  -D{build.board} -DARDUINO={runtime.ide.version}  -DACTIVE_REGION=LORAMAC_{build.band}  -DLORAWAN_DEVEUI_AUTO={build.LORAWAN_DEVEUI_AUTO} -DLORAWAN_DEVEUI_AUTO={build.LORAWAN_DEVEUI_AUTO} -DLORAWAN_CLASS={build.LORAWAN_CLASS} -DLORAWAN_NETMODE={build.LORAWAN_NETMODE} -DLORAWAN_ADR={build.LORAWAN_ADR}   -DLORAWAN_UPLINKMODE={build.LORAWAN_UPLINKMODE}  -DLORAWAN_NET_RESERVE={build.LORAWAN_Net_Reserve}  -DAT_SUPPORT={build.LORAWAN_AT_SUPPORT} -DLoraWan_RGB={build.RGB} -DLoRaWAN_DEBUG_LEVEL={build.LORAWAN_DebugLevel} -DSOFT_SE -DARDUINO_ARCH_ASR6601 -D__{build.core}__ -D__{build.mcu}__ "-I{compiler.sdk.path}/drivers/peripheral/inc/"  "-I{compiler.sdk.path}/drivers/crypto/inc/" "-I{compiler.sdk.path}/platform/CMSIS/"  "-I{compiler.sdk.path}/platform/system/" "-I{compiler.sdk.path}/lora/driver/" "-I{compiler.sdk.path}/lora/radio/" "-I{compiler.sdk.path}/lora/"  "-I{compiler.sdk.path}/lora/radio/sx126x/" "-I{compiler.sdk.path}/lora/system/" "-I{compiler.sdk.path}/lora/system/crypto" "-I{compiler.sdk.path}/base/" "-I{compiler.sdk.path}/" "-I{compiler.sdk.path}/peripheral/" 
+compiler.cpreprocessor.flags.asr6601=-D{build.band}  -D{build.board} -DARDUINO={runtime.ide.version}  -DACTIVE_REGION=LORAMAC_{build.band}  -DLORAWAN_PREAMBLE_LENGTH={build.LORAWAN_PREAMBLE_LENGTH} -DLORAWAN_DEVEUI_AUTO={build.LORAWAN_DEVEUI_AUTO} -DLORAWAN_DEVEUI_AUTO={build.LORAWAN_DEVEUI_AUTO} -DLORAWAN_CLASS={build.LORAWAN_CLASS} -DLORAWAN_NETMODE={build.LORAWAN_NETMODE} -DLORAWAN_ADR={build.LORAWAN_ADR}   -DLORAWAN_UPLINKMODE={build.LORAWAN_UPLINKMODE}  -DLORAWAN_NET_RESERVE={build.LORAWAN_Net_Reserve}  -DAT_SUPPORT={build.LORAWAN_AT_SUPPORT} -DLoraWan_RGB={build.RGB} -DLoRaWAN_DEBUG_LEVEL={build.LORAWAN_DebugLevel} -DSOFT_SE -DARDUINO_ARCH_ASR6601 -D__{build.core}__ -D__{build.mcu}__ "-I{compiler.sdk.path}/drivers/peripheral/inc/"  "-I{compiler.sdk.path}/drivers/crypto/inc/" "-I{compiler.sdk.path}/platform/CMSIS/"  "-I{compiler.sdk.path}/platform/system/" "-I{compiler.sdk.path}/lora/driver/" "-I{compiler.sdk.path}/lora/radio/" "-I{compiler.sdk.path}/lora/"  "-I{compiler.sdk.path}/lora/radio/sx126x/" "-I{compiler.sdk.path}/lora/system/" "-I{compiler.sdk.path}/lora/system/crypto" "-I{compiler.sdk.path}/base/" "-I{compiler.sdk.path}/" "-I{compiler.sdk.path}/peripheral/" 
 compiler.c.flags.asr6601=-c -mcpu=cortex-m4 -mthumb -w -Wall -g -gdwarf-2 -MMD -Os -mapcs-frame -fno-common -ffat-lto-objects -ffunction-sections -fdata-sections -std=gnu99 -fno-builtin-printf -fno-builtin-sprintf -fno-builtin-snprintf  
 compiler.cpp.flags.asr6601=-c -mcpu=cortex-m4 -mthumb -w -Wall -g -gdwarf-2 -MMD -Os -mapcs-frame -mthumb-interwork -fno-common -ffat-lto-objects -ffunction-sections -fdata-sections  -fno-builtin-printf -fno-builtin-sprintf -fno-builtin-snprintf -fno-builtin-fflush  -Wno-strict-aliasing -c -fno-exceptions -fexceptions -fno-rtti
 compiler.S.flags.asr6601=-c -mcpu=cortex-m4 -mthumb