User's Manual

CT-EM2506 ZigBee Ready RF Transceiver Modules

13. SIF Module Programming and Debug Interface

SIF is a synchronous serial interface developed by Cambridge Consultants Ltd. It is the

primary programming and debug interface of the CT-EM2506. The SIF module allows

external devices to read and write memory-mapped registers in real-time without

changing the functionality or timing of the XAP2b core.

The SIF interface provides the following:

 IC production test (especially analog)

 PCB production test

 XAP2b code development

 Product control and characterization

The pins are:

 SIF_LOADB

 SIF_CLK

 SIF_MOSI

 SIF_MISO

The maximum serial shift speed for the SIF interface is 48MHz. SIF interface accesses

can be initiated even when the chip is in idle and deep sleep modes. An edge on

SIF_LOADB wakes the chip to allow SIF cycles.

14. Power Management

The CT-EM2506 supports three different power modes: processor ACTIVE, processor

IDLE and DEEP SLEEP.

The IDLE power mode stops code execution of the XAP2b until any interrupt occurs or an

external SIF wakeup command is seen. All peripherals including the radio continue to

operate normally.

The DEEP SLEEP power mode powers off most of the module but leaves the critical chip functions,

such as the GPIO pads and RAM powered by the High Voltage Supply (VDD_PADS). The module

can be woken by configuring the sleep timer to generate an interrupt after a period of time, using an

external interrupt, or with the SIF interface. Activity on a serial interface may also be configured to

wake up the module, though actual reception of data is not re-enabled until the module has finished

waking up. Depending on the speed of the serial data, it is possible to finish waking up in the middle

of a byte. Care must be taken to reset the serial interface between bytes and discard any garbage data

before the rest. Another condition for wakeup is general activity on GPIO pins.