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  1. H

    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 ?

    Your advice is more than enough. A google search for "PIC SPI Bootloader" uncovered among others this information:https://legacy.nrao.edu/alma/memos/html-memos/alma414/memo414.pdf Problem solved. The answer is: Yes, an established SPI bus will be sufficient. Thanks Abaz Regards Henning
  3. H

    [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...
  4. H

    Creating a "Bus busy" signal.

    Thanks for all your replies. I have been reading up on the CAN bus and it seams that it better meets my needs. I think I'll give the CAN bus a try. Thanks.
  5. H

    Creating a "Bus busy" signal.

    Hi Alexandros. I do agree polling would be the standard way to go. The thing is I have to create a solution with very high focus on power efficiency. The network, when completed will have up to 200 nodes and it will be on 24/7. 90% of the nodes will just monitor some sensors and if the sensor...
  6. H

    Creating a "Bus busy" signal.

    It is a rs485 network. It is wired with cat5. Bus length max 100meters/300feet. 1 twisted pair for power, one for GND and one for rx/tx (The last pair is reserved) Nodes will primarily be monitoring temperature, humidity, smoke detector, PIR etc. in a building. I know I could implement...
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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...
  8. H

    Adding a Master-Wake-Up signalto the rs-485 bus ?

    Would this work for signaling the master ?
  9. H

    [SOLVED] I need a a-fixed-value-device ?

    Thanks skogsjanne.
  10. H

    [SOLVED] I need a a-fixed-value-device ?

    Ah that's smart. What is a RC-link exactly ? (I assume it involves a Resistor and a Capacitate)
  11. H

    [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...
  12. H

    Adding a Master-Wake-Up signalto the rs-485 bus ?

    It'll be a single-master system. Well, to save bandwidth and power. In a system where 99% of the traffic and a large part of the power consumption is "wasted" it just seamed a good idea. (Haven't done the math on the power consumption part, just guessing) That is a very good idea!
  13. H

    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 ?

    Thank you cubanflyer, this is perfect.
  15. H

    [SOLVED] Reading a dip switch using one pin ?

    Thanks. Why ? Could you put a few more words on this concept ? Any idea of what appropriate resistor values would be ? (Im running 5volts on the slave) Regards
  16. H

    [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...

    Arigh... That I don't get. I'll read up on "shift register" so I fully understand what a shift register does. I'll get back. ---------- Post added at 23:32 ---------- Previous post was at 22:55 ---------- Well I do get it (I think) The clue was (taken from the 74HC595 datasheet): - And the...
  18. H

    [SOLVED] One PIC, a lot of LEDs to Pulse Width Modulate...

    Yes, that make sense, that's clever. Very clever. I got it. In the links you provided there was also a discussion on controlling A LOT of leds using shift registers and BAM. I'm a bit confused about the shift registers.... The shift registers has nothing to do with the BAM-concept, right ...
  19. H

    [SOLVED] One PIC, a lot of LEDs to Pulse Width Modulate...

    Thanks klug, this was very interesting. I'll need to google Binary Code Modulation a bit more and find some schematics, I don't quite get the theory/concept yet.

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