SIM900 alternative

[hussamaldean]

Hi all,
I am currently working on a project that uses GSM-GPRS to communication to send certain data at certain rate. however, SIM900 is very slow and I have to delay the commands otherwise, it won't be able to keep up with the data stream required.
is there any GSM-GPRS module that supports SPI protocol ?
I think with SPI, I will be able to get better results due to fact that SPI is much faster at rate of 4MHz

regards

[hussamaldean]

Hi all,
I am currently working on a project that uses GSM-GPRS to communication to send certain data at certain rate. however, SIM900 is very slow and I have to delay the commands otherwise, it won't be able to keep up with the data stream required.
is there any GSM-GPRS module that supports SPI protocol ?
I think with SPI, I will be able to get better results due to fact that SPI is much faster at rate of 4MHz

regards

Do you think your data is being choked by UART/SPI/I2C, or by GPRS?

If you get crappy GPRS, no local communication bus can save you.

You need an LTE module. Consider SIM7000G.

the data is being chocked by UART not the communication between SIM900 and the server since I have to send just a string which contains only about 60 characters

[hussamaldean]

any help ?

[Marco]

the data is being chocked by UART not the communication between SIM900 and the server since I have to send just a string which contains only about 60 characters

So you don't really care how fast it goes to the server, but you absolutely want those 60 characters to get to the modem as fast as possible? Why?

[hussamaldean]

the data is being chocked by UART not the communication between SIM900 and the server since I have to send just a string which contains only about 60 characters

So you don't really care how fast it goes to the server, but you absolutely want those 60 characters to get to the modem as fast as possible? Why?

in case if the internet went down, I need to send thousands of those strings to the server as fast as possible
so, needing a faster  communication between SIM and ESP32 is a must at least I can send a certain data and don't have to wait for a response from the SIM module.
All I need just to tell me if the end server reports 200 or other case.

[mikerj]

I think you will be disappointed, GPRS is just slow with a maximum throughput of only 85.6 kbps for the SIM900 module.  If you are running the USART at 115.2 kbs you shouldn't have a bottleneck.

[hussamaldean]

I think you will be disappointed, GPRS is just slow with a maximum throughput of only 85.6 kbps for the SIM900 module.  If you are running the USART at 115.2 kbs you shouldn't have a bottleneck.

I tried to send the command without any delay and the results are the SIM didn't even start the HTTP connection

[Marco]

What's your USART code like? Do you have a CTS interrupt?

[hussamaldean]

What's your USART code like? Do you have a CTS interrupt?

ISR is handling important stuff like instantly update the value of certain registry when one of the inputs is changed. so, implanting such interrupt won't serve me anything since the data I receive is only when I receive the status of 200 otherwise I shall repeat the scenario.
 

[FreddieChopin]

if latency is important then use UDP or raw sockets (works on XP without SP1)

[Marco]

implanting such interrupt won't serve me anything since the data I receive is only when I receive the status of 200 otherwise I shall repeat the scenario.
 

You still need flow control, either RTS/CTS or XON/XOFF ... do you have flow control?

[hussamaldean]

if latency is important then use UDP or raw sockets (works on XP without SP1)

the server requires JSON format and I have to use HTTP due to server limitation

[FreddieChopin]

if latency is important then use UDP or raw sockets (works on XP without SP1)

the server requires JSON format and I have to use HTTP due to server limitation

Well there's your problem. First you use bloated HHTP and then bloat it even further with JSON. With right assembly code you can get few Mbit/s speed out of bock standard USART.

[hussamaldean]

if latency is important then use UDP or raw sockets (works on XP without SP1)

the server requires JSON format and I have to use HTTP due to server limitation

Well there's your problem. First you use bloated HHTP and then bloat it even further with JSON. With right assembly code you can get few Mbit/s speed out of bock standard USART.

few Mbps will be impossible since the module maximum baud rate is 115200bps

[Marco]

Without flow control higher transfer rate between your microcontroller and the modem will just help you to screw up faster.

[FreddieChopin]

Then maybe you could use USB-OTG host library and use LTE modem? They are very very fast.

[hussamaldean]

Then maybe you could use USB-OTG host library and use LTE modem? They are very very fast.

could you please elaborate ?

[mikerj]

I think you will be disappointed, GPRS is just slow with a maximum throughput of only 85.6 kbps for the SIM900 module.  If you are running the USART at 115.2 kbs you shouldn't have a bottleneck.

I tried to send the command without any delay and the results are the SIM didn't even start the HTTP connection

That doesn't sound like it's the fault of the UART.  Does your carrier even support GPRS, many do not?

A 4G USB dingle is cheap and very fast, but driving it from a microcontroller is much harder and requires one with USB OTG.  Could you maybe use something like a Raspberry Pi?

[hussamaldean]

I think you will be disappointed, GPRS is just slow with a maximum throughput of only 85.6 kbps for the SIM900 module.  If you are running the USART at 115.2 kbs you shouldn't have a bottleneck.

I tried to send the command without any delay and the results are the SIM didn't even start the HTTP connection

That doesn't sound like it's the fault of the UART.  Does your carrier even support GPRS, many do not?

A 4G USB dingle is cheap and very fast, but driving it from a microcontroller is much harder and requires one with USB OTG.  Could you maybe use something like a Raspberry Pi?

great solution but we don't have 4G in Iraq