Hi,
I have a question regarding the transmission duration in the Online Power Profiler for BLE (OPP). More precisely, it is about the transmission duration during a connection in the peripheral mode.
Settings:
{
"chip": "2",
"voltage": "3",
"dcdc": "on",
"lf_clock": "lfxo",
"radio_tx": "0",
"ble_type": "con",
"ble_int": "100",
"tx_size": "0",
"rx_size": "0",
"phy": "2mbps",
"slave_latency": "0",
"central_ppm": "20",
"peripheral_ppm": "20"
}
In my understanding, the size and transmission duration an empty BLE packet is
- LE 1M PHY
- 10 byte: 1 byte preamble + 4 byte access address + 2 byte PDU + 3 byte CRC
- --> 80 µs transmission duration = 10 byte * 8 bit / byte / (10^6 bit / s)
- LE 2M PHY
- 11 byte: 2 byte preamble + 4 byte access address + 2 byte PDU + 3 byte CRC
- --> 44 µs transmission duration = 11 byte * 8 bit / byte / (2 * 10^6 bit / s)
However, I measure a transmission duration of 128 µs for both the LE 1M PHY and the LE 2M PHY in the OPP. Moreover, increasing the payload by 1 byte increases the transmission duration by 8 µs on the LE 2M PHY, whereas it should be 4 µs.
This results in a transmission duration of 336 µs for 26 byte payload (128 µs + 26 * 8 µs). Now, when the payload is increased by 1 byte to 27 (without packet length extension), the transmission duration decreases to 148 µs. This almost aligns with the theoretical value (44 µs + 27 byte * 4 µs / byte = 152 µs).
Could you please verify if there is a bug?
Thank you!
