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    Home automation: Human presence

    Hi I'm trying to build a smart house. To be smart, the house needs to know where people are located. Having all individuals to carry some sort of transmitter is not an option. I need the lights to turn on in the bedroom even if I'm wearing nothing but a towel. To detect human presence I think...
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    [SOLVED] Can a PIC be programmed over the SPI bus ?

    Hi. I'm (trying) to design a CANbus node for my home automation project. Any given node consist of a main-board with a power supply circuit, a PIC18F26K80 and a demultiplexer to handle the chip select of up to 8 daughter boards. A daughter board will at have a (small) PIC running in SPI slave...
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    Creating a "Bus busy" signal.

    Hi Let's say I have 10 nodes/microcontrollers on the same data bus. The nodes are powered by the same power line (Was thinking 24v). I was wondering if I could use this shared power line to send a signal when a node wants to use the data bus. I was thinking this: 1. When a node is turned on...
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    [SOLVED] I need a a-fixed-value-device ?

    I have 4 PCB's with a microcontroller on each. The boards are identically in both hardware and software. Now when powered on I would like MCU A to run subroutine A, MCU B to run subroutine B and so on. - so I need a way to tell each MCU what to run. This could be done with at dip switch and a...
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    Adding a Master-Wake-Up signalto the rs-485 bus ?

    Adding a Master-Wake-Up signal to the rs-485 bus ? Hi. I have a rs-485 network with one master and multiple slaves. A slave is only speaking if spoken to by the master. Let's say I have a slave that monitors a sensor. If the sensor value gets outside a predefined range the master must be...
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    [SOLVED] Reading a dip switch using one pin ?

    Hi. I am trying to design a simple rs485 slave. The slave will get its address from a 5 position Dip switch. It will only need to read the switch once: When it is powered on. (Storing the address in a register for later use) I could dedicate 5 pins on the microcontroller to this purpose, but...
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    [SOLVED] One PIC, a lot of LEDs to Pulse Width Modulate...

    Hi. I would like to use one PIC to control the PWM for let's say around 200 LEDs. The PIC should be able to adjust the brightness/PWM of each LED alltough time is not critical. All I want to do is to "dim led no. 63 5% somewhere around 5:00pm. If it gets 5:10pm thats fine too" No hurry. I...
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    What does ""active low" mean ?

    Hi. I'm new to all this and learning every day. This might be a very basic question and I do think I have understand it the correct way, just need to be sure. I have a quad bus buffer, the 74HC125. In the data sheet it says: This means that if there is no signal going to the !OE pin the...
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    [SOLVED] Switching rs485 bus, how ?

    Hi. I have two rs485 networks and a slave node that need to shift between these two networks. It will not be frequent shifts and it is fine if the shifting takes some time. Time is not critical. My PIC does not have 2 uart's. Something like this: What can I use as a switch (The blue box)...
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    [SOLVED] Power to a microcontroller network... (rs485)

    Hi. I'm planning to make a network of microcontrollers as part of a home automation system. I was thinking of a rs485 network. As I understand it, for a full duplex rs485 network I'll need 3 twisted pairs. So if I use a cat5 cable I'll have one twisted pair not in use. Is it a good idea to use...
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    [SOLVED] Connecting sub-boards to a PIC

    Hi I'm sure there is a "standard" way to solve this problem. I just don't know it. Here is my thoughts. If I have a PCB that should be connected to a PIC (using 4 pins) on another PCB, then I'll just connect the two with a cable. Now let's say I have 16 PCBs I need to connect to the same PIC...
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    [SOLVED] What component will do this ?

    Hi. I'm new to all this, but I'm trying to design a circuit for a computer controlled mixer. I'm still at the basics but learning every day. I need a "device/component" that's nothing more that a switch, but it should switch on 4 (or 5) circuits at once. The switch should be controlled by a...
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    [SOLVED] Uart Daisy chaining, possible ?

    Hi Although I've been making PC-software for quite some years now, I'm just at the beginning of my journey into the world of microcontrollers. I'm trying to figure out how I can build a computer controlled audio mixer. (8 inputs 16 individually stereo outs) To build this mixer, I plan to...

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