Xbee circuit help
I'm working on a remote sensor network using xbee's. I could use some help on the shchematic and the board layout. I've attached what I've come up with, however I'm sure there are better ways to do it. The sensor is battery powered (2x AA batteries) and runs at 3.3v via a bost conerter, so low waste power is important. Currently it's got a mag switch (normally open) and a tmp36 on it (more will come later). There is also an ISP header. The way have the p-channel mosfet in the power supply should provide reverse voltage protection with minimal waste power. I'm not sure how to all over voltate protections to this without a signifigant cost (money and power). Everything in the circuit can survive 5 volts execpt the xbee. For this reason, there's a manual switch to enable and disable the isp header. When the header is enabled the xbee's power and serial input are disconnected. As I'm typing this, I'm thinking I should probably add a simple diode on the vcc line of the header to protect from reverse voltage. As far as the board layout goes. There is a ground plane on the top and bottom layers with vias near components. Any via labeled "tp#" is a test point. All buyt 2 traces are on the top of the board. The signal traces are 12mil and the power traces are 21mil. The micro enables/disables the xbee and tmp36 via their sleep pins and checks if the mag switch goes from ground to high. Any help/suggestions would be much apprechiated as I've never designed something like this before . Thanks.
- schematic.jpg (123.22 KiB) Viewed 934 times
- board.jpg (162.95 KiB) Viewed 934 times