3.2 Operating Modes Overview

The following figure illustrates an overview of the operating modes supported by the ATA5835:

Figure 3-3. Operating Modes Overview

After connecting the supply voltage to the VS pin, the ATA5835 always starts in OFFMode. All internal circuits are disconnected from the power supply; therefore, SPI communication is not supported. The ATA5835 can be woken up by activating the PWRON pin or one of the NPWRONx pins. This triggers the power-on sequence. After the initialization, the system reaches the IDLEMode.

The IDLEMode is the basic system mode supporting SPI communication and transitions to all other operating modes. There are two options of the IDLEMode requiring configuration in the EEPROM settings:

IDLEMode(RC) with low-power consumption using the Fast RC (FRC) oscillator for processing
IDLEMode(XTO) with active crystal oscillator for high-accuracy clock output or timing measurements

In the IDLEMode, the firmware cycles through the main loop. If there are no pending tasks during a main loop cycle, the processor system automatically switches into the configured SleepMode.

The TXMode enables data transmission using the selected service/channel configurations. It is usually enabled by the SPI command, “Set System Mode”, or directly after power-on when selected in the EEPROM setting. A system mode change can also be triggered by user Flash software.

The RXMode provides data reception on the selected service/channel configuration. The receiver continuously scans for a valid telegram and receives the data if all preconfigured checks are successful. The RXMode is usually enabled by the SPI command, “Set System Mode”, by user Flash software or directly after power-on when selected in the EEPROM setting.

In PollingMode, the receiver is activated for a short period of time to check for a valid telegram on the selected service/channel configurations. The receiver is deactivated if a valid telegram is not found. The SleepMode is entered until the polling cycle timer elapses. This process is repeated periodically in accordance with the polling configuration. The initial settings are stored in the EEPROM and copied during firmware initialization to the SRAM. This allows modification of the PollingMode timing and service/channel configuration during IDLEMode.

The TCMode offers calibration and self-checking functionality for the VCO and FRC oscillators, as well as for temperature measurement and polling cycle accuracy. This mode is activated via the SPI command, “Calibrate and Check”, or Flash software. When selected in the EEPROM settings, tune and check tasks are also used during system initialization after power-on. Furthermore, they can also be activated periodically during the PollingMode.

The following table shows the relation between the operating modes and their corresponding power supplies, clock sources and SleepMode settings.

Table 3-1. Operating Modes versus Power Supplies and Oscillators
Operation Mode	AVR^® SleepMode	DVCC	AVCC	VS_PA	XTO	SRC	FRC
OFFMode	—	off	off	off	off	off	off
IDLEMode(RC)	Active mode  Power-down⁽¹⁾	on	off off	off off	off off	on on	on off
IDLEMode(XTO)	Active mode  Power-down⁽¹⁾	on	on on	off off	on on	on on	off off
TXMode	Active mode	on	on	on⁽²⁾	on	on	off
RXMode	Active mode	on	on	off	on	on	off
PollingMode(RC) - Active period - Sleep period	Active mode  Power-down⁽¹⁾	on	on off	off off	on off	on on	on off
PollingMode(XTO) - Active period - Sleep period	Active mode  Power-down⁽¹⁾	on	on on	off off	on on	on on	off off

Note:

During the IDLEMode(RC) and the IDLEMode(XTO), the AVR microcontroller enters the SleepMode to reduce the current consumption. The SleepMode of the microcontroller section can be defined in the EEPROM. The power-down configuration is recommended for keeping the current consumption at a minimum.
Only activated at 5V applications. This is selectable in the EEPROM settings.