ESB payloads occasionally sent off later than expected

RE: ESB payloads occasionally sent off later than expected

esmart-engineering — Tue, 07 Jan 2025 22:06:41 GMT

I see; that makes sense. Thank you for the info! I appreciate it.

RE: ESB payloads occasionally sent off later than expected

Kenneth — Tue, 07 Jan 2025 22:02:18 GMT

Hi,

I don't expect lowering it is possible no. Have in mind that switching from tx to rx (to receive the ack) and vice versa is about 130us each way. In addition you need to spend the necessary time in rx or tx (to send/receive the on-air data), which can be a couple of hundreds of us depending on the on-air datarate and payload size.

Kenneth

RE: ESB payloads occasionally sent off later than expected

esmart-engineering — Tue, 07 Jan 2025 21:15:53 GMT

Thank you for confirming that my hypothesis was correct. So is this problem/delay unavoidable? Are there ways to minimize that delay even more? For example, I would have expected lowering the retransmit delay could help lower the delay but my experiments seem to suggest that it doesn't; is this expected behavior?

RE: ESB payloads occasionally sent off later than expected

Kenneth — Tue, 07 Jan 2025 20:47:22 GMT

Hi,

I don't see any specific questions here, other than a confirmation that it make sense, and it absolutely does.

If you for instance get yourself an Power Profiler Kit II you can measure the current with high timing precision, and actually observe the exacting timing of tx and rx: https://www.nordicsemi.com/Products/Development-hardware/Power-Profiler-Kit-2

Kenneth

RE: ESB payloads occasionally sent off later than expected

Simonr — Tue, 07 Jan 2025 15:17:40 GMT

We are looking into this. Thank you for your reminder. We'll get back to you by end of week.

Best regards,

Simon

RE: ESB payloads occasionally sent off later than expected

esmart-engineering — Fri, 03 Jan 2025 20:46:11 GMT

Just wanted to add a kind reminder for your ESB expert to take a look at this post on the 6th. Looking forward to your thoughts on this.

RE: ESB payloads occasionally sent off later than expected

esmart-engineering — Fri, 20 Dec 2024 20:23:38 GMT

I already clarified this in my previous reply - packets are late, and logic analyzer only is used for timing. Please have your ESB experts address this when they get back Jan 6.

RE: ESB payloads occasionally sent off later than expected

Simonr — Fri, 20 Dec 2024 10:11:31 GMT

What makes the packet receive what seems to be early here though (4ms - 5.5ms - 7 ms)? Do you have a log or something showing the timings here or do you take them just based on the logic analyzer?

Best regards,

Simon

RE: ESB payloads occasionally sent off later than expected

esmart-engineering — Thu, 19 Dec 2024 18:28:39 GMT

I corrected the example about when the packets are coming in, to show why the packet is getting sent late.

I measured timing using LEDs and a logic analyzer (and, to clarify again, using the ESB examples heavily as a starting point)

I rewrote the LED code used in the ESB examples so that leds_update(uint8_t value) will toggle led<value>. For example, leds_update(0) toggles led0, which is LED1 on the nRF5340DK
On PTX, I toggle led0 before and after the esb_write_payload() call
On PTX, I toggle led1 twice when handling ESB_EVENT_TX_SUCCESS.
On PRX, I toggle led0 twice when handling ESB_EVENT_RX_RECEIVED.
I hooked up a logic analyzer to those LEDs and measured timing this way.
- PTX led0 toggles every 2ms as expected.
- PTX led1 and PRX led0 shows the occasional late packet.

The packets do use ACKing (on PTX, I set tx_payload.noack = false).

RE: ESB payloads occasionally sent off later than expected

Simonr — Thu, 19 Dec 2024 08:48:55 GMT

I guess tis could be the Auto Retransmit delay that does this, which is at least 0.5ms. How would you explain this behavior exactly on your end? Since the payloads come in at 4ms, then 5.5ms, it sounds like the packet is early, not late? Can you show us how exactly you measure the timing here, and do you do ACKing or not?

Unfortunately, our ESB experts have left for the holiday season, so you won't have any expert advice until January 6th I'm afraid.

Best regards,

Simon