No flow control on SIM7600CE-T 4G(LTE)

Hardware Arduino GSM Shield
1

I've been working with the

LTE SIM7600 SIM7600CE-T_4G(LTE)_Shield_V1.0_SKU_TEL0124-DFRobot

for a few weeks now, with an Arduino Uno. The LTE has SSL/MQTT onboard and I'm using it to communicate with AWS IOT. I have it connecting and publishing short messages back and forth.

The LTE is connected on pins 7,8 using SoftwareSerial . I figured out that I had to slow down the baud rate to 9600 between the LTE and Arduino AND the Arduino/PC usb port, in order to get the SSL certificates loaded onto the LTE without corruption. I found I had to use "slow write" code like this;

loop
modem.write(data); / 10 bytes at a time
pause
repeat until finished

in order to get the certs copied accurately. My understanding is that the USB port does have flow control but I'm now certain that the Arduino/LTE virtual serial port does not. I know the Uno can't do flow control on 7,8. And I've now confirmed that the LTE doesn't have flow control support either - received response from inquiry to DFRobot. They state there are no pins available on the LTE for RTS/CTS.

I found I had to both slow the baud rate to 9600 AND had to use the slow write code above to get it to work. Is this commonly done? Am I missing something?

I don't understand how a cell modem board can be useful for transmitting data without a solid serial port with flow control. For example this LTE board boasts "up to 150Mbps for downlink and 50Mbps for uplink data transfer" well it can't do that if the LTE/Arduino port is hamstrung at 9600 baud or slower without flow control. What am I missing?

I'm a long time software engineer (30 years) but new to firmware/Arduino. Lot's to learn so I appreciate any and all clues, advice etc.

Thanks
Mike

2

I just started working with the same SIN76700CE-T module. I also had issues at higher baud rates - although it seemed ok at 57600.

Did you try changing the port that the device communicates on? On my module there are jumpers to change pins between 7/8 and 0/1 - you can then use the hardware port of the Arduino to communicate.

3

red_Car and 1mikemakuch- what country are you in?
Can someone tell me if the 7600CE-T will work in the USA?
I have to replace a 3G comm project with LTE and may have purchased the 7600CE-T in error for USA use.

I appreciate your help. i had a 3G->Arduino project running flawlessly for 4 years and need to replace.

4

I am in New Zealand.

Not sure about USA.

In this post someone was asking similar... I found a link that seemed to indicate one provider might work.

5

I am in USA, yes SIM7600 was working here in USA, Texas. I was using Hologram.io

6

Is that with the 7600CE-T version?

7

Please see my original post where I state clearly what I was working with.

8

I usually don't bother reading back through all the posts from 8 months ago - enjoy the rest of your day.

9

Yeah thats a good way to get help

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10

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