Hi,
I am pretty new to arduino, but come from embedded software development, but this is my first time into electronics, so please dont make me feel too stupid Here is my question:
I have a sensor which comunicates via rs232 and then I must send that data via gprs to a website. I found the hwkitchen gprs module and the one at eshopen.com. The first one apparently doesnt use the serial line pins, which would be free for the sensor. Up until here I could use a mini. There are also other options that I would like to add which is an sd module for local logging (I do believe I can attach this to the mini, and finally a gps.
Will all of this fit on the mini? I have doubts, and I found multiple gps some of them use digital inputs (so the combination gprs module + gps + sensor + sd via spi should work) others instead use the rx of the serial line, but I believe that is not a solution since the mini has only one serial line right?
Also just to know, what are the steps you guys do to produce a bunch of them after the prototype (Id like to remove some unused components from the hwkitchen).
To my knowledge, it should be feasible. The only thing taking up a few pins, is the sd card. Start with this, and then work your way to count the pins required, and if they need to be connected to a special function (ie specific pin).
The rs232 issue can be solved using a max232 chip. See how by googling 232 on the arduino site, but don't use that schematics, use the one from the datasheet instead.
To create your own pcb, you can use Eagle from cadsoft.de. Sparkfun has a tutorial on how to make your own pcbs using eagle.
Hi thanks for bringing up the rs232 issue, I thought that the arduino serial rx and tx were actually rs232. All I have coming from the sensor is two cables, one is 5V for powering it and the other one is a signal, therefore I thought of simply attaching it to the RX port of the Arduino.
Am I wrong, I always used rs232 along with the ftdi but the usual 3 cables.
Also now they told me that the sensor Has analog output with ±5V each axis (reconstituted from digital data using 12 bit D/A). I could also use this other solution and use two analog pins. This way I would still have the serial port for a serial line gps. I was worried of not having enough serial lines, and in the end I might not even use them!
The RS232 standard specifies the electrical characteristics for data communications. A signal between +3V and +15V is high and a signal between -3V and -15V is low.
Usually, when people mention RS232, they're also talking about sending 8-bit characters, using a start bit and one or more stop bits.
When you send a character through the Arduino serial port, you are sending out a start bit, the character, and a stop bit, but the electrical signal is 0V for low and 5V for high, so you can't plug it into a device that is expecting an RS232 signal.
Fortunately, there's an easy solution If you connect a MAX232 chip to the two serial pins, it will convert the signal from 0 - 5VDC (also known as TTL) to a valid RS232 signal.
The Arduino libraries also have routines that can turn any two digital pins into a serial port. This is referred to as a "soft" serial port. It has some limitations, so it's not as versatile as the built-in hardware serial port on pins 0 and 1.
If you have two devices that have TTL serial ports, you can connect them together without converting to RS232. For example, two Arduinos can communicate this way, by connecting TX to RX and RX to TX. Don't forget to connect the grounds together.
Here is my question: