You can use the QED Board’s RS485 link to create such a multi-drop serial network. The RS485 protocol uses differential data signals for improved noise immunity; thus RS485 can communicate over greater distances than RS232. RS232 uses inverse logic; that is, a positive bit at the 68HC11 UART is inverted by the onboard RS232 driver chip and appears as a negative signal on the serial cable. Serial 2 is implemented by a software UART in the controller’s QED-Forth Kernel that uses two of the processor’s PortA I/O pins to generate a serial communications channel. Thus, the master 68HC11 has only one input, MISO, which is the slave QVGA Controller’s only output. Thus, resetting the SPIF flag is very simple. In this chapter we will consider the most general and simple configurations. In this section we will consider the most general and simple configurations. Please contact Mosaic Industries if you need these custom configurations.

Setup is the same when multiple meters are interconnected via cables CBL03, except that all meters now need to be set to a different digital address via their front panel. Question:I can't connect to the device at address 192.168.0.7 to change the address and connect to my network. Regardless of the network, however, there are only four signals used: SCK provides a synchronized clock, MOSI and MISO signals are used for data transmission and reception, what is rs485 cable and /SS configures the 68HC11 as a master or slave device. Configured as a master device, the 68HC11 transmits bytes via the "master out/slave in" pin, MOSI. The CPOL and CPHA bits configure the synchronous clock polarity and phase and specify when valid data is present on the MISO and MOSI data lines. Use Laurel’s 6-wire data cables CBL03-1 (1 ft) and CBL03-7 (7 ft) to interconnect meters if these lengths fit your application. The secondary channel is very useful for debugging application programs that communicate with other computers or I/O via the primary channel. Since both channels can operate simultaneously and independently, debugging can be performed while the application program is communicating via its primary channel. The primary channel’s UART translates the bit-by-bit data on the serial cable into bytes of data that can be interpreted by the QED-Forth Kernel or by your application program.

The SCK (serial clock) pin is a configurable synchronous data clock output. If the /SS pin of the master is an output, it can be controlled independently of the SPI system. WARNING: Do NOT connect this device to a telephone system under any circumstances. Damage could result to the circuit board and/or your telephone system. 6 hardware, are provided on the circuit board. If your computer does not have an RS-232 serial port, low cost USB-to-RS-232 serial cables are available; contact Mosaic Industries for details. The QScreen Controller combines an embedded computer based on the 68HC11 microcontroller with a touch panel and LCD (liquid crystal display) graphic user interface (GUI) that is ideal for instrument control and automation. The QVGA Controller makes it easy to configure a multi-drop network of QVGA Controllers controlled by a single master desktop computer. This setting is only relevant for the master device, as it is the master’s clock which drives the transfer. Also, in the diagram, the master’s /SS (slave select) is configured as an output. Also, in the diagram, the master QVGA Controller’s /SS (slave select) is configured as an output. The next section describes the registers that configure and control the QVGA Controller’s SPI.

This allows the processor that is master to control the input /SS pins of other CPU’s, for example. There are a variety of ways the MOSI, MISO, SCK and /SS pins on your QVGA Controller can be connected. Hardware is interfaced to the SPI via four PORTD pins named /SS, SCK, MOSI, and MISO brought out to pins 11 through 14 on the Digital I/O connector (see Appendix A). Most computers conform to IBM PC AT-compatible RS232 interfaces which use 9-pin D-Type connectors, consequently the QScreen Controller brings out its serial ports to two female 9-pin D-Type connectors. RS232’s greatest benefit is its universality; practically all personal computers can use this protocol to send and receive serial data. It provides a convenient means of connecting the QVGA Controller to a variety of peripheral devices, including analog to digital and digital to analog converters, real time clocks, and other computers which use high speed communication.