Note: VCHAR is used as a supply voltage for charging control parts
Note: VCHAR is used as a supply voltage for charging control parts
Power Up and Reset
Power up and reset is controlled by the UEM ASIC. NHM-8NX baseband can be powered up in following ways:
1 Press power button, which means grounding the PWRONX pin of the UEM
2 Connect the charger to the charger input
3 Supply battery voltage to the battery pin
4 RTC Alarm, the RTC has been programmed to give an alarm
After receiving one of the above signals, the UEM counts a 20ms delay and then enters it's reset mode. The watchdog starts up, and if the battery voltage is greater than Vcoff+ a 200ms delay is started to allow references etc. to settle. After this delay elapses the VFLASH1 regulator is enabled. 500us later VR3, VANA, VIO and VCORE are enabled. Finally the PURX line is held low for 20 ms. This reset, PURX, is fed to the baseband ASIC UPP, resets are generated for the DSP and the MCU. During this reset phase the UEM forces the VCXO regulator on regardless of the status of the sleep control input signal to the UEM. All baseband regulators are switched on at the UEM power on except for the SIM regulator that is controlled by the MCU. The UEM internal watchdog is running during the UEM reset state, with the longest watchdog time selected. If the watchdog expires the UEM returns to power off state. The UEM watchdog is internally acknowledged at the rising edge of the PURX signal in order to always give the same watchdog response time to the MCU.
When the Power on key is pressed the UEM enters the power up sequence as described in the section Power Up and Reset. Pressing the power key causes the PWRONX pin on the UEM to be grounded. The UEM PWRONX signal is not part of the keypad matrix. The power key is only connected to the UEM. This means that when pressing the power key an interrupt is generated to the UPP that starts the MCU. The MCU then reads the UEM interrupt register and notice that it is a PWRONX interrupt. The MCU now reads the status of the PWRONX signal using the UEM control bus, CBUS. If the PWRONX signal stay low for a certain time the MCU accepts this as a valid power on state and continues with the SW initialization of the baseband. If the power on key does not indicate a valid power on situation the MCU powers off the baseband.
In order to be able to detect and start charging in a case where the main battery is fully discharged (empty) and hence UEM has no supply (NO_SUPPLY mode of UEM) charging is controlled by START-UP CHARGING circuitry.
Whenever VBAT level is detected to be below master reset threshold (VmstrJ charging is controlled by START_UP charge circuitry. Connecting a charger forces VCHAR input to rise above charger detection threshold, VCHdet+. By detection start-up charging is started. UEM generates 100mA constant output current from the connected charger's output voltage. As battery charges its voltage rises, and when VBAT voltage level higher than master reset threshold limit (Vmstr+) is detected START_UP charge is terminated.
Monitoring the VBAT voltage level is done by charge control block (CHACON). MSTRX='1' output reset signal (internal to UEM) is given to UEM's RESET block when VBAT>Vmstr+ and UEM enters into the reset sequence described in section Power Up and Reset.
If VBAT is detected to fall below Vmstr- during start-up charging, charging is cancelled. It will restart if new rising edge on VCHAR input is detected (VCHAR rising above VCH-det+).
Baseband can be powered up by connecting battery with sufficient voltage. Battery voltage has to be over UEM internal comparator threshold level, Vcoff+. Battery low limit is specified in Table 2. When battery proper voltage is detected UEM enters to reset sequence as described in section Power Up and Reset. This power up sequence is meant for test purposes, in normal use (Btemp resistor > 1kQ) the phone will power off again immediately, without noticing the user.
If phone is in POWER_OFF mode when RTC alarm occurs the wake up procedure is as described in section Power Up and Reset. After baseband is powered on an interrupt is given to MCU. When RTC alarm occurs during ACTIVE mode the interrupt for MCU is generated.
The UEM contains the following A/D converter channels that are used for several measurement purposes. The general slow A/D converter is a 10 bit converter using the UEM interface clock for the conversion. An interrupt will be given at the end of the measurement.
The UEM's 11 -channel analog to digital converter is used to monitor charging functions, battery functions, voltage levels in external accessory detection inputs, user interface and RF functions.
When the conversion is started the converter input is selected. Then the signal processing block creates a data with MSB set to '1' and others to '0'. In the D/A converter this data controls the switches which connect the input reference voltage (VrefADC) to the resistor network. The generated output voltage is compared with the input voltage under measurement and if the latter is greater, MSB remains '1' else it is set '0'. The following step is to test the next bit and the next., until LSB is reached. The result is then stored to ADCR register for UPP to read.
The monitored battery functions are battery voltage (VBATADC), battery type (BSI) and battery temperature (BTEMP) indication.
The battery type is recognized through a resistive voltage divider. In phone there is a 100kOhm pull up resistor in the BSI line and the battery has a pull down resistor in the same line. Depending on the battery type the pull down resistor value is changed. The battery temperature is measured equivalently except that the battery has a NTC pull down resistor in the BTEMP line.
KEYB1&2 inputs are made for keyboard scanning purposes. These inputs are also routed internally to the miscellaneous block. KEYB1&2 inputs are not used In NHM-8, and the connected interrupts must be kept disabled by SW.
The HEADINT and HOOKINT are external accessory detection inputs used for monitoring voltage levels in these inputs. They are routed internally from the miscellaneous block and they are connected to the converter through a 2:1 multiplexer.
PATEMP and VCXOTEMP channels are not used as originally intended. PATEMP input is used for detection of accessory covers (CTI), VCXOTEMP is not used in NHM-8.
Number of bits
Was this article helpful?
You can now recondition your old batteries at home and bring them back to 100 percent of their working condition. This guide will enable you to revive All NiCd batteries regardless of brand and battery volt. It will give you the required information on how to re-energize and revive your NiCd batteries through the RVD process, charging method and charging guidelines.