User Guide

RM-11

Troubleshooting - Baseband CC Technical Documentation

Power Up and Reset

Power up and reset are controlled by the UEM ASIC. The RM-11 baseband can be

powered up in the following ways:

• By the Power button, which means grounding the PWRONX pin of the UEM

• By connecting the charger to the charger input

• By the RTC alarm, when the RTC logic has been programmed to give an alarm

After receiving one of the above signals, the UEM counts a 20ms delay and enters into

reset mode. The watchdog starts up, and if the battery voltage is greater than Vcoff+,

a 200ms delay starts to allow references (etc.) to settle. After this delay elapses, the

VFLASH1 regulator is enabled. Then, 500us later the VR3, VANA, VIO, and VCORE are

enabled. Finally, the power-up reset (PURX) line is held low for 20 ms. The PURX reset is

fed to the baseband UPP ASIC. Resets are generated for the MCU and the DSP. During

this reset phase, the UEM forces the VCTCXO regulator on — regardless of the status of

the sleep control input signal — to the UEM. The FLSRSTx from the ASIC is used to reset

the flash during power up and to put the flash in power down during sleep. All baseband

regulators are switched on when the UEM powers on. The UEM internal watchdogs are

running during the UEM reset state, with the longest watchdog time selected. If the

watchdog expires, the UEM returns to the power-off state. The UEM watchdogs are

internally acknowledged at the rising edge of the PURX signal in order to always give the

same watchdog response time to the MCU.

Figure 2 represents the UEM start-up sequence from reset to power-on modes.