If the programmer has enabled the local interrupt mask for the SPI, an interrupt is recognized at this point. SPIE is a local interrupt mask that allows an interrupt to be recognized when an SPI data transfer has completed, or if a write collision or mode fault is detected. The QScreen allows the details of the synchronous communications protocol to be customized for compatibility with a variety of peripherals. The RS485 interface allows the creation of multipoint networks. The Serial Peripheral Interface, SPI, is a fast synchronous serial interface. Depends what you mean by a serial cable - Fibre, Ethernet, RS232, RS485, RS422, USB, HDMI, SMPTE292 are all examples of serial communications media. There are a variety of ways the MOSI, MISO, SCK and /SS pins on your QScreen Controller can be connected. All Rights Reserved. The material on this site can not be reproduced, distributed, transmitted, cached or otherwise used, except with prior written permission of Answers.

For the QScreen, /SS is not used for SPI communication because it is used to control the direction of the RS485 transceiver; you can use any digital I/O line as a /SS signal. RTS- signals are all employed as handshake control signals. These signals are described in detail below. The DWOM bit (port D wired-or mode) should always be set to 0. Setting DWOM to 1 takes away the processor’s ability to pull the Port D signals high unless there is a pull-up resistor on each bit of the port. This setting is only relevant for the master device, as it is the master’s clock which drives the transfer. Configured as a master device, the QScreen transmits bytes via the "master out/slave in" pin, MOSI. The InitSPI() function provides a convenient way to initialize the SPI as the master at a 2MHz baud rate. The two lowest order bits in the SPCR control register, named SPR1 and SPR0, determine the data exchange frequency expressed in bits per second; this frequency is also known as the baud rate. The next section describes the registers that configure and control the QScreen Controller’s SPI. This chapter describes those drivers, and presents code that makes it easy to configure the SPI for different data transfer rates and formats.

Consult the data sheets for any peripheral devices that you are interfacing to the SPI and, if a different configuration is needed, follow the instructions below to set up the appropriate SPI data transfer protocol. Although many applications use RS-485 signal levels, the speed, format, and protocol of the data transmission are not specified by RS-485. In general, all devices on a network should use the same phase, polarity, and baud rate clock signal. In some cases, however, a sophisticated network may have device groups on a network that use different clock configurations. RS485 cable is a type of communication cable commonly used in industrial settings for connecting devices in a network. After connecting as for point B, in the Settings it is possible to define a name for the device, and if the reading periodicity is less than 250 minutes, you can set an interval of hours in which the reading is not carried out / transmitted (for example you can disable the night). Transmissions are always initiated by the master device, and consist of an exchange of bytes. If you are using the QScreen as a slave device and require the /SS signal for your external SPI hardware, configure one of the Port A pins on the Field Header as an input pin.

The SCK pin clocks the serial A/D’s CLK input which causes the A/D’s conversion result to be transferred to the master via the MISO line. Only one active master may control the network at a time; however, the device that assumes the role of master may change according to an appropriate protocol. RESOURCE and the access control functions GET() and RELEASE(). Any of these conditions may generate an interrupt if the SPIE (SPI interrupt enable) bit in the SPCR control register is set. The QED-Forth kernel includes pre-coded drivers that configure and control the SPI for maximum speed data transfers. The /SS (active-low slave select) is typically used to enable data transfers by slave devices when it is active low. Although data byte transfers are easily executed once the network has been wired and configured properly, a carefully executed software protocol may be required to ensure data integrity. It is interesting to measure the humidity of the ground, but we have also thought about other things; and then we have TXtemp to measure the temperature (one of the uses of TXtemp is in association with SuperClock), and for practically any type of measurement we have TXdata (RS232, RS485 ModBus) - which can be connected to thousands of existing third-party professional RS232 or ModBus meters (and there is something for all needs: temperature and humidity meters, anemometers, voltage meters, energy, light meters, water meters, presence sensors, brightness sensors, soil humidity sensors, etc. ; practically all professional meters are available in ModBus or RS232 standard; and not just meters).