HL7588 AT Latency & Throughput

IoT Modules Legacy HL Series
1

Hello! I am using a HL7588 modem over Serial UART , 115200 baud (firmware RHL75xx.V.3.15.151600.201802071640.x7160_1) . I’ve noticed I’m having particularly slow configuration and responses over the uart. Each AT command is taking quite a while for configuration and to receive a response. For instance, these following timing for AT commands is common place:

AT+KUDPCFG: 112-285+ ms
AT+KUDPSND: 7-12ms
EOF-MARKER: ~128ms
AT+KUDPCLOSE: 12ms

With these timings, it can take me over 400ms just to get the UDP overhead accomplished (plus the actual transmit time for the data I’m sending).

Two questions:

  1. is this normal, or did I get a defective modem?
  2. how can I speed this up over serial?

I’m using as Teensy 3.6 to configure the modem. I need to use a small embedded device upstream of the modem, so that rules out adding PPP etc over USB. Is there a way to optimize this so I can send a single packet in less than 1/2 of a second over UART?

Things I’ve tried:

  • I am using hardware control flow.
  • I tried setting up “warm” UDP contexts so I could cut out the KUDPCFG overhead, but to send to another context, I still have to close the previously used context.
  • I’ve adjusted the baud rates to higher rates in common between the Teensy and Modem. However, this only shaved a couple (less than 10) ms off total times.

Any insight or recommendations from anyone would be greatly appreciated!

Thanks!

2

Hi,

It’s normal you get around 400ms to get the above UDP accomplished.
I got the similar timing as you in my HL dev-kit even with USB IF connected with my PC.
It seems cannot speed up much even with good signal, high UART baudrate.

3

Thank you for letting me know! I was starting to think I was missing something.

Thanks!