FONA Communication Speed

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Hiraghm
 
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FONA Communication Speed

Post by Hiraghm »

okay, so I connect my FONA to my RPi at 115,200bps.
So if I use my FONA to connect to the internet, using 3G... I'm still transferring data to my RPi at dial-up speeds, aren't I?

If I download a file off the internet, if I connect to a website... the data transmitted and received is still bottlenecked at that 115,200 communication speed with the FONA, isn't it?

So, can I up the communication speed between the RPi and the FONA?
Or can I connect to the FONA a different way, say via I2C or some such, so that I can get the advantage of full 3G internet speed?

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adafruit_support_mike
 
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Re: FONA Communication Speed

Post by adafruit_support_mike »

The major bottleneck will be the speed of your Serial connection, yes.

The GSM module has a USB port and interface, but we don’t have any information about working with that.

The FONA’s Serial port can operate at speeds higher than 115200, but you’ll have to test the RasPi to see how fast its Serial port will go.

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Hiraghm
 
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Re: FONA Communication Speed

Post by Hiraghm »

Thanks for the info.

if I did the math right, 1 megabit per second would be 131,000 bytes per second, roughly.
That's a good internet speed.
I'd have to set the serial port to 8388608 to match that.
I suppose I could tie its usb port into one of the RPi's usb port, and then get megabit speeds?
Hate to give up yet another usb port, though.
Still, if I did it that way, it would free up the rx & tx pins of the Pi for something else.

is it possible to connect the PI's serial pins to RS232? I've some vintage computers I'd love to be able to connect to it via RS232.

Anyway, thanks again for patiently curing my ignorance :)

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adafruit_support_mike
 
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Re: FONA Communication Speed

Post by adafruit_support_mike »

Hiraghm wrote:I suppose I could tie its usb port into one of the RPi's usb port, and then get megabit speeds?
Maybe, but we really don't know. We only use the USB interface on rare occasions for things like firmware upgrades.
Hiraghm wrote:is it possible to connect the PI's serial pins to RS232? I've some vintage computers I'd love to be able to connect to it via RS232.
It depends on the hardware.

Strictly speaking, RS-232 is just the wiring standard, and puts no restrictions on the kinds of signals you use. In practice, older computers used RS-232 wiring to transmit +/-9V-to-15V differtential signals (one line goes high when the other goes low) using the UART communication protocol.

A RasPi's Serial port obeys the parts of the UART protocol associated with the TX and RX signals, but doesn't support any of the flow-control signals. It also doesn't use differential signals or positive/negative line voltages.

There are chips that translate a RasPi's TX/RX UART signals to the kind of signals older computers used, but setting them up is a little involved.

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