SetRxDutyCycle parameters for LoRa P2P based on RAK4631

WisBlock
1

Hi,
according to the RAK4631-Deep-Sleep-P2P example code for Arduino, the rx_time and sleep_time parameters are set to the following values:

uint32_t duty_cycle_rx_time = 2 * 1024 * 1000 * 15.625;
uint32_t duty_cycle_sleep_time = 10 * 1024 * 1000 * 15.625;

However, according to the SX1261 Calculator Tool, the symbol time for SF7 and BW125KHz is 1.024ms … so from my understanding, this value is 1.024ms * 1000us/ms = 1024us

In addition, according to the SX1261/2 Datasheet:

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… so, probably i’m not correct, but according to this, should not be the rx_time and sleep_time parameters set to:
uint32_t duty_cycle_rx_time = 2 * 1.024 * 1000 / 15.625;
uint32_t duty_cycle_sleep_time = 10 * 1.024 * 1000 / 15.625;

Sorry in case my mistake is obvious. Any help will be appreciated. Thanks.

2

You might be right.
I always get confused with the different documentation about calculating timing on the SX1262.

3

Hi @beegee thanks for yout reply … I agree that there are many not clear references. Any member can share him/her experience on this issue? I think It is important to clarify it. Thanks.

4

Hi @beegee, i’ve made some experiments in order to check how to corretly set the duty_cycle_rx_time and duty_cycle_sleep_time parameters for RXDutyClycle functionality, and here are some of the results i obtained. I set the following parameters in RAK4631-Deep-Sleep-P2P example code for Arduino:

#define RF_FREQUENCY               868000000 
#define TX_OUTPUT_POWER            22 
#define LORA_BANDWIDTH             0 
#define LORA_SPREADING_FACTOR      7
#define LORA_CODINGRATE            1 
#define LORA_PREAMBLE_LENGTH       100  
#define LORA_SYMBOL_TIMEOUT        0 
#define LORA_FIX_LENGTH_PAYLOAD    false
#define LORA_IQ_INVERSION_ON       false
#define RX_TIMEOUT_VALUE           3000
#define TX_TIMEOUT_VALUE           3000

For a preamble lenght of 100 symbols, the number of symbols for rx and sleep were calculated to be 8 and 96, respectively, i.e. 8,192ms and 98,304ms. So, in order to use this values, the duty_cycle_rx_time and duty_cycle_sleep_time parameters were set as following:

uint32_t duty_cycle_rx_time = (8 * 1.024 * 1000) / 15.625;     
uint32_t duty_cycle_sleep_time = (96 * 1.024 * 1000) / 15.625;

From this values, the following results were obtained by using PPK2 from Nordic, where the time interval for rx_time and sleep_time seem to correspond to the calculated values …

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… and here are the results for the following parameter values, with a preamble lenght of 250 symbols:

uint32_t duty_cycle_rx_time = (8 * 1.024 * 1000) / 15.625;     
uint32_t duty_cycle_sleep_time = (246 * 1.024 * 1000) / 15.625;

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Hope it helps in case I’m right.

1 Like