KBL-179.jpg' alt='Bafo Usb To Serial Port Driver' title='Bafo Usb To Serial Port Driver' />View and Download Bafo BF120 user manual online. USB TO IrDA ADAPTER. BF120 Adapter pdf manual download. Paulo 49074 So 46318 do 40723 Brasil 38043 da 37922 Da 35214 US 33367 Folha 2900 Local 19724 Reportagem 1790 Jos 15364. Online Robotics store in india,Buy Robotic Kits, Microcontroller Boards, Motor Drivers Sensors. Bafo Usb To Serial Port Driver' title='Bafo Usb To Serial Port Driver' />Raspberry Pi Driving a Relay using GPIOTheres something exciting about crossing the boundary between the abstract world of software and the physical real world, and a relay driven from a GPIO pin seemed like a good example of this. Although a simple project, I still learned some new things about the Raspberry Pi while doing it. There are only four components required, and the cost for these is around 7. Even a cheap relay like the Omron G5. LA 1 5. DC can switch loads of 1. A at 2. 40. V. A word of caution dont tinker with mains voltages unless youre really really sure about what youre doing. A mechanical relay allows a safe learning environment, since you can switch any load with it e. V DC batterybulb circuit for testing, and the concept of a mechanical switch is very easy to grasp. A more efficient alternative to switch an AC load would be to use a solid state relay e. Triac, but its quite easy to make a wrong assumption and blow everything up with a loud bang and a big spark. I recommend sticking with mechanical relays until youre entirely sure about what youre doing. Tip you can buy plug in low voltage AC power supplies if you want to play with triacs. The Circuit. There are four components to this circuit. A relay 5. V DC coil, a BC3. NPN transistor, a diode, and 1. K resistor. Essentially, the transistor is used to energise the relays coil with the required voltage and current. A relay will often have 3 significant voltagecurrent ratings specified coil, AC load, and DC load. LA/TI/MY-6366772/usb-to-serial-converter-bafo-make-500x500.jpg' alt='Bafo Usb To Serial Port Driver' title='Bafo Usb To Serial Port Driver' />The most important to our circuit is the coil rating, which is the current at a specified voltage required to energise the coil activate the switch, sometimes expressed as milliwatts m. W. The AC and DC load ratings relate to the switch contacts, and state the maximum load current e. AC and DC voltages. DC loads are rated lower because they arc spark more, which eventually wears the contacts to the point of failure. In general, large loads need heavier contacts, which in turn need bigger coils to switch them, and bigger coils need more power from your circuit. Saber Power Electronics Simulation. Relays sometimes dont fit easily onto a breadboard, so you might want to build the circuit on veroboard instead, or just mount the relay on veroboard and add two pins for the coil contacts allowing you to breadboard it. Dont ever put AC mains into your breadboard Schematic for a relay via GPIO on the Raspberry Pi. The GPIO pin used in the example code is GPIO1. Raspberry Pis 2. GPIO1. PCMCLK and beside GPIO2. PCMDOUT. The choice of GPIO 1. I considered it less likely to conflict with other peripherals likely to be in use. Although the pin is marked 3. V on the schematic, dont confuse this with the 3. V3 pin I labelled it with the voltage to highlight that a 3. V GPIO pin is driving a 5. V load it could also drive a 2. V coil, for example, if an appropriate DC power supply is used rather than the Raspis 5. V line. Essentially, to activate the relay, all the circuit does is send a few milliamps at 3. V from the GPIO pin, through a 1. K resistor you may choose to increase this to 1. K if you want to be strictly below 3m. A. This current is enough to saturate the BC3. V rail through the transistor, and therefore also through the relays coil. Most general purpose NPN transistors with an minimum h. FE of say 5. 0 to 1. BC3. 37 it will depend on a how much current youre willing to draw from the GPIO pin, b how much current is required to energise the relays coil, c the actual h. FE of the transistor in your hand, since they vary wildly and the current gain could easily be significantly more than the stated minimum. The diode in the circuit is there to conduct the current generated by the de energising coil back across the coil e. Take care to orient the diode correctly, or youll short 5. V to ground via the transistor when the GPIO is high. Similarly, take care to correctly identify the collector, base, and emitter pins on your transistor. The pin ordering varies by type, so check the datasheet. Id recommend you double check these two components before powering up. The breadboard photo shows it wired up. The pin numbering on my IDC plug should be though of from above the connector, to make it correspond with the 2. Blue is 5. V, and brown is Ground. The green wire connects from GPIO 1. Raspis 2. 6 pin header to the transistor base via resistor R1. You can test that the relay is working by disconnecting the wire from GPIO 1. V3 pin 1. You should hear a click as you connectdisconnect 3. V3. Make sure you keep the resistor in the circuit e. V3 to the transistors base pin. Note that the circuit assumes the GPIO pin will be configured as an output. If its likely to also spend some time as an input, then a resistor 1. K would do between the base and ground would ensure the transistor is fully off, rather than having a floating voltage applied. Using the relay via the sys filesystem. Enable GPIO 1. 7 access via the Kernel on path sysclassgpio, and configure it as an output pin echo 1. View the current state of GPIO 1. Set the state of GPIO 1. Finally, to use the C code instead, remove the pin from the control of the Kernel driver echo 1. The C Code Alternative. The C source code below shows how to drive the relay using the GPIO peripherals hardware registers. Its all in one file for simplicity and for clarity, though theres not much to it. The usleep1 call has been used to create a short delay before reading the LEVn register to feed back the pin status. This is because the rise time for a GPIO pin the time for the voltage on the pin to rise to a level thats considered high is around 1. V. The high threshold is probably less than half that, but even if its 3. ARM clock cycles at 7. MHz, and is enough time to read the LEVn register before it has transitioned. GPIO peripheral on a BCM2. Raspberry Pi. Copyright 2. Kevin Sangeelee. Released as GPLv. This is intended as an example of using Raspberry Pi hardware registers to drive a relay using GPIO. Use at your own. risk or not at all. As far as possible, Ive omitted anything that doesnt relate to the Raspi registers. There are more. conventional ways of doing this using kernel drivers. IOBASE   0x. 20. 00. GPIOBASE IOBASE 0x. GPFSEL0    gpio. GPFSEL1    gpio. GPFSEL2    gpio. GPFSEL3    gpio. GPFSEL4    gpio. GPFSEL5    gpio. Reserved word offset 6. GPSET0    gpio. GPSET1    gpio. Reserved word offset 9. GPCLR0    gpio. GPCLR1    gpio. Reserved word offset 1. GPLEV0    gpio. GPLEV1    gpio. BIT1. 7 1 lt lt 1. PAGESIZE 4. 09. 6. BLOCKSIZE 4. 09. GPIOBASE. Some forward declarations. Failed to map the physical GPIO registers into the virtual memory space. Modern Epidemiology Third Edition here. Set GPIO 1. 7 as an output pin. GPFSEL1 7 lt lt 2. Mask out bits 2. 3 2. GPFSEL1 i. e. force to zero. GPFSEL1 1 lt lt 2. Set bits 2. 3 2. GPFSEL1 to binary 0. GPCLR0 BIT1. 7. GPSET0 BIT1. Delay to allow any change in state to be reflected in the LEVn, register bit. GPIO 1. 7 is sn, GPLEV0 BIT1. Exposes the physical address defined in the passed structure using mmap on devmem. Open devmem. if p memfd opendevmem, ORDWROSYNC lt 0. Failed to open devmem, try checking permissions. BLOCKSIZE. PROTREADPROTWRITE. MAPSHARED. p memfd,  File descriptor to physical memory virtual file devmem. Address in physical map that we want this memory block to expose. MAPFAILED. perrormmap.