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> Black 12 key kepad for with serial interface
Black 12 key kepad for with serial interface
Twelve Key Keypad with a Serial Interface - BV4505
The BV4505 is a 12 key keypad with a serial interface. This makes it ideal for interconnecting to systems with the minimum of hardware. It can be connected directly to a PC COM port or a microcontroller. As this has a 16 key buffer the processor resources are not wasted scanning keys.
It has a 16 key first in first out buffer so that the host software does not need to continually scan the keypad. There is also a key down detect for key repeat applications or linear control. Full data sheet can be found at http://www.byvac.co.uk/bv/datasheets/BV4505 DataSheet.pdf
* Connects directly to a PC com Port or via a USB, BV101
* Connects directly to a microcontroller serial port
* 12 soft touch key switches
Keys can be pressed without the intervention of the host microcontroller and they will be stored in the key buffer for collection later. This frees up the overhead on the host. There are four simple commands that allow access to the device, these are:
* 'b' Read number of keys in buffer
* 'd' Discover if key is down
As an additional feature is that command 'd' can determine if the key is actually being pressed at the time the command was sent, this can be useful for implementing key repeat features or events that require the key to be pressed for a certain length of time.
The serial interface consists of 5 connections, of which, only four will be used at any one time. The connection details are as follows:
There are two interface options, RS232 via a standard PC COM port (Pins 4 and 2) or from a microcontroller UART (pins 1 and 2). As an example to interface to a standard 9 pin D type connector the following connections would be made.
Only three wires are required from the COM port to the BV4505. There is no hardware handshaking so the pins in the above table should be connected together as indicated (1,6,4: 9 and 8). Connection to a microcontroller would be similar except that pin 1 would be used instead of pin 4.
The interface is fully configurable by software commands. From the factory the software will detect the Baud rate automatically, this is achieved by pressing CR two or three times. The Baud rate is selected from 9600, 14400, 19200 and 38400.
There is also available the same board but with an I2C interface (BV4506).
