First project hardware advice req.

I have a couple of questions about what hardware to pick up for my first project. The final implementation of what I'm planning will probably have the following features, and I just want to make sure that the stuff that I pick up initially will at least support what I'm wanting to do. What I'm wanting to do is read from a serial connection NMEA 0183 (from a depth finder + GPS)(Assuming I need to convert from RS232 to TTL) Buffer the data to an SD card Use bluetooth to connect to a phone/tablet when a connection is established with the Arduino.

So what I'm wondering is: 1) Most of the bluetooth shields/modules that I've been reading about seem to want to be connected to the RX/TX lines, but I'm thinking that those need to be connected to the NMEA line; do I need to get a Mega2560 in order to get the additional serial line(one for reading serial, one for BT comms)? 2) SD card stuff seems fairly straight forward from what I can tell; 3) Is there anything that I should be watchful for with respect to wanting to connect the Bluetooth to a phone/tablet (I'm thinking of connecting to a PlayBook because that's what I've currently got. (And I will hopefully be able to get bluetooth stuff working there)) Intent is that the BT connection should be compatible with Apple, Android, BlackBerry phones/tablets (but intents aren't necessarily reality)

Many thanks for any advice :)

You can use the NewSoftSerial library to do (software) serial IO on arbitrary pins - I think its interrupt driven so should 'just work'. A Mega2560 might not be required (but having more pins can be useful for other things later).

Any SPI shield must use the ICSP header for SPI bus to be compatible with the Mega series of boards since Hardware SPI is on different Arduino pins (the ICSP header however is identical between Arduino and Mega).

svanderw:

  1. Most of the bluetooth shields/modules that I’ve been reading about seem to want to be connected to the RX/TX lines, but I’m thinking that those need to be connected to the NMEA line; do I need to get a Mega2560 in order to get the additional serial line(one for reading serial, one for BT comms)?

Yes, however, I think I’ve seen somewhere around the forum a new chip with some Serial ports that you can interface with SPI or I2C. I’m quite sure there are some of those available… but in the end, the size of your code, will have an impact on which Arduino to choose.

Max232 can be used to do that translation… although I’m not so sure you need that. A similar chip I like is DS275, since it uses no capacitors :smiley:

svanderw:
2) SD card stuff seems fairly straight forward from what I can tell;

It is, if you use the libraries… otherwise, not so much.

svanderw:
3) Is there anything that I should be watchful for with respect to wanting to connect the Bluetooth to a phone/tablet (I’m thinking of connecting to a PlayBook because that’s what I’ve currently got. (And I will hopefully be able to get bluetooth stuff working there)) Intent is that the BT connection should be compatible with Apple, Android, BlackBerry phones/tablets (but intents aren’t necessarily reality)

I don’t know much (if anything) about BT, but if you truly want to make it accessible to anyone, why not using WiFi? With a Mega, you could probably make a server that would serve info in HTML or accept connections using a telnet-like approach.
In terms of power consumption, I’m not sure if there is a substantial difference.

The reason I wasn't really thinking WiFi was because this project will be hanging out in a boat once it's complete, completely out of the range of most WiFi routers. I also don't believe my phone (nor tablet) will currently supply a WiFi hotspot either.

Thanks for the info about the NewSoftSerial; that should resolve my issue wrt serial ports, and I am now thinking that the UNO should be sufficient for my project :) BT shield looks like it uses 0,1 SD shields look like they take pins 10-13, (or 8, 11-13 depending on the model) I'll use 2,3 with NewSoftSerial for reading the serial data, Leaves me with plenty of room to hook up a bunch more inputs if I need/want to (and I'm sure I will at some point :) ).

I'm thinking that I only need BT Slave communications (if I'm reading the documentation correctly) as I will be establishing the BT connection from the phone/tablet to the Arduino.

Again thanks for helping out a newbie :)