Logic Components; 1 ] Cpu; 2 ] Eeprom; Key, Led Circuit - Brother P-Touch QL-570 Service Manual

2.3.1

Logic Components

[ 1 ] CPU
CPU (U7) controls and manages the entire system, which is 32 bit microcomputer of NEC
brand. This CPU contains the 256 Kbyte ROM that stores the control program data. The
embedded 24 Kbyte RAM is used mainly for temporary storage of incoming data from PC.
[ 2 ] EEPROM
One 4Kbit EEPROM (U2) is used. This memory is used for write and storage of Vendor ID
code, Product ID code and mechanical information. If the main PCB ASSY is replaced, it is
needed to write the serial number printed on the EEPROM mounted on the main PCB ASSY
and the mechanical configuration data. For this operation, refer to "APPENDIX 1
MAINTENANCE SOFTWARE OPERATION".
2.3.2

Key, LED Circuit

(1) Power supply ON/OFF circuit
This circuit detects the state of ON/OFF of the ON/OFF button. Pressing this button in the
power supply OFF state (LED OFF), LOW signal is sent to the CPU. Then the CPU starts
initializing process and establishes the status of power supply ON (LED ON and ready for
data acceptance from PC). Pressing this button in the condition that the status of power
supply is ON and the status of ready for data acceptance from PC (LED ON), the CPU starts
power OFF process, turns the LED OFF and changes the status into power supply OFF (LED
OFF). Pressing this button in the condition that the status of power supply is ON and now
going on printing, the CPU stops printing, starts power OFF process after reading and
discarding the data sent from PC, and changes the status into power supply OFF (LED OFF).
(2) Feed button ON/OFF circuit
Pressing this button, this circuit activates the tape feed motor ASSY and it feeds a medium by
a certain distance. This motion does not involve printing.
(3) Cut button ON/OFF circuit
Pressing this button, this circuit activates the cutter motor ASSY and it cuts a medium.
(4) LED ON/OFF circuit
This circuit turns the LED on, off and makes it blinking according to the status of power
supply ON/OFF and some error conditions. For more details, refer to section "4.3 LED
Control in Different Situations and Measure Against Errors".
SWLED PCB
Fig. 2.3-2 Key, LED Circuit
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