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3-6
3.4.2
Power Up / Power Down Sequence
Powering up the radio can be initiated by turning the ON/OFF knob to ON position or an ON
command from the Patriot IC through BUS_PWR_OUT line. These actions will trigger the ATTiny13
microcontroller to start the power up sequence by asserting the 5V_EN. Once 5V_EN is high, the
U2200 will turn ON and MOSFET Q2202 that will turn ON the transceiver via SW_B+.
Supply from 5V will power up Power Management IC U2100 which has its own defined sequencing
for its 4 output voltages. The 1.55V supply will start to ramp and once the peak is reached the other
voltages (3.3V, 1.88V and 2.8V) will start. The reset lines, POR and MPU_RESET from the U2200
will remain low for 1 second to hold OMAP in the reset mode the moment 5V is applied to U2100.
Once the Reset lines are asserted high, the OMAP IC will start and software will commence. The
OMAP will send a 1ms low true signal to the ATTiny13 through line B+_CTRL to indicate OMAP's
software has started so as to cancel a reset pulse from ATTiny13. The assumption is that if OMAP IC
failed to start within 8 seconds from the assertion of 5V_EN, ATTiny13 will force a reset on the
system.
For powering down, the trigger would begin by turning the ON/OFF knob to OFF position or an OFF
command from Patriot IC through BUS_PWR_OUT. ATTiny13 microcontroller and OMAP IC's
ON_OFF_SENSE will be triggered to initiate the shutdown sequence. ATTiny13 microcontroller
would de-assert 5V_EN which would turn OFF the 5V Regulator IC (U2200) and turns OFF
MOSFET Q2202 in which SW_B+ will drop and initiate a shutdown of the transceiver section.
3.4.3
Reset Circuits
A reset will occur when OMAP IC or Patriot IC sends a reset command to the ATTiny13
microcontroller through B+_CTRL or BUS_PWR_OUT respectively. To reset, ATTiny13
microcontroller will drop 5V_EN low for 2 seconds, in which the whole radio system will reset.
When 5V_EN is dropped, POR will be high, 5V switching regulator (U2200) will go off and SW_B+
will be low. Brick_5V will reset the flip-flop (U2302) and ensure that the brick did turn off. When
5V_EN is back to high after 2 seconds, the whole system will power up again.
3.4.4
ATTiny13 Microcontroller Programming
As with all microcontrollers, software resides in the ATTiny13 microcontroller. If upgrade is
necessary, programming can be accomplished through the use of a specially made ATTiny13 Flex
cable.
The flex is to be connected to P2300 and at ALL TIMES the volume knob must be in the OFF
position. ATMEL's AVRISP programming kit is to be attached on the other end of the flex. A+ must be
supplied to the control head for UNSW_VCC in order to power the AVRISP and ATTiny13
microcontroller.
For a list of programming kits needed, please refer to
Part Number
8416228H01
AVR ATTiny13 Programming Flex
(Motorola Part
Number)
ATAVRISP
AVR ISP Programmer
(ATMEL Part
Number)
June 15, 2005
Table 3-2. ATTiny13 Programming Kit
Description
Theory of Operation: Power Management
Table
3-2.
Application
To be used with XTL 1500 control head to reprogram
the ATTiny13.
Device used to program ATMEL range of ATTiny
Microcontrollers.
6815854H01-A
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Troubleshooting
