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This with WiFi transmission for the Standard version, and in the RF version also with radio transmission at 433MHz (covering longer distances and with less battery consumption thanks to special optimizations). 2) the GSM version also allows you to indicate a possible PIN (leave blank if there is no PIN) and the operator's APN (possibly you can search for it on Google). 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. When this bit is high, the transceiver is in transmit mode. If SPIF is set, rs485 cable reading the received data or initiating a new data transfer automatically clears the SPIF bit. Also, several non-serial interrupts can stack up; if they have higher priority than the serial interrupts, they will be serviced before the Serial2 interrupt routine, and again a serial input or output bit may be lost. The one you choose depends on the specific device, or devices you will be connecting to. If you are using the QScreen as a master device, each external SPI device will require a separate select line (/SS). Configured as a master device, the QScreen transmits bytes via the "master out/slave in" pin, MOSI.

A data transfer is initiated by a master device when it stores a message byte into its SPDR register. The remaining "inactive" slaves may actively receive, or listen to, data on the communications line, but only one slave at a time can transmit a message. It may be that only the byte sent from the master to the slave is meaningful; nevertheless, each device simultaneously transmits and receives one byte. The InitSPI() function provides a convenient way to initialize the SPI as the master at a 2MHz baud rate. The Serial2 channel is always configured for RS232 communications, and can sustain baud rates up to 4800 baud. Pre-coded device drivers configure the SPI for a standard data format, and it is easy to customize a data format and baud rate for your application. The BufferToSPI() function implements fast data transfer from a specified buffer in the controller’s memory to an SPI device.

The device that initiates a data transfer is the master, and all other devices on the network are slaves. The interface can be used to support analog to digital and digital to analog converters, networks of many computers controlled by a single master, or networks of devices controlled by several coordinated masters. A ground connection is also necessary to ensure that the communicating devices have a common voltage reference. In some cases, however, a sophisticated network may have device groups on a network that use different clock configurations. You can use the QScreen’s RS485 link to create such a multi-drop serial network. The SCK (serial clock) pin is a configurable synchronous data clock output. By polling the Port A pin or by setting up an interrupt service routine, you can configure the QScreen to ignore the SCK input when /SS is high and keep MISO in a high-impedance state so that it does not interfere with the SPI bus. Remember that the /SS is active low so to select a device you need to set the pin low; otherwise the pin should idle high. The status of a device as master or slave determines how the various pins must be configured.

Note that the data is changed by the transmitting device one half clock cycle before it is valid. This automatically activates the SCK clock which synchronously transmits the data. This function properly configures the directions of the SPI I/O pins, and configures the data transfer such that data is valid on the falling trailing edge of the clock, with the clock idling in the low state. 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. These steps greatly reduce the chance that the communicating devices might be damaged by contention on the SPI bus. Any required SPI output signals must be configured as outputs, either by calling InitSPI() or by setting the appropriate bits in the Port D data direction register DDRD. As the master transmits its data, 8 bits of data are simultaneously received.