Samsung SF-335T Repair Manual

Also see for SF-330 Series: Quick install guide Operating instructions User manual Service guide

Contents

CIRCUIT DESCRIPTION3.2 OPE3.2.1 Basic Concept3.2.2 UART Operation3.2.1.1 OverviewOPE BOARD is separated from the Main Board functional-ly, and operates entire Micom(HT48C5A-000Z) in theBoard. OPE and Main exchange mutual information usingUART(universal asynchronous receiver/transmitter) chan-nel. Also, Resetting of OPE is designed to control at theMain. Micom in OPE performs key-scanning and LCD, LEDdisplay control, and senses document detect, Scan positionand so on. When information is generated from OPE(keytouch, sensor level change, etc.), it sends specific codecoping with the situation to Main, and the Main operatessystem by analyzing this code. If the Main tries to displaydata on OPE, the Main sends data to OPE via UART lineon the basis of the format specified, and OPE displays it toLCD.In the case of the TAD Model, the MIC for the SpeakerPhone and OGM and the Pre-Amp part of the MIC havebuilt-in at OPE circuit.3.2.1.2 UARTOPE and MAIN exchange information mutually by usingasynchronous communication mode(UART), and in fullduplex. Band rate is 9600bps, and uses 7.37MHz resonatoras oscillating element. It engages in communication with8bit data without parity bit. UART line has two lines for Txand Rx, and the default level is in the 'high' state. For com-munication, the start bit(low level) is transmitted before 8bitdata. When the data transmission(8bit) is completed, thehigh state is maintained as the stop bit(high level) is trans-mitted. Data is transmitted from LSB(DO), and MSB(D7) istransmitted lastly.3.2.2.1 UART Communication<1> UART TX FORMATCodes for change of KEY, TOUCH, SENSOR LEVEL andso on are transmitted in single code without PRE/POSTDATA, and OK or Error messages to check if communica-tion is performed properly are also transmitted in singlecode. Provided that, in case the Main requested a certainvalue(LCD, other register) particularly, data requested istransmitted followed by sending Post Data('EOH') first.<2> UART RX FORMATData being received will be arranged to be received accord-ing to the following specified format to know what data theyare.DATA are received in the sequence of A,B,C, and D, andthe Check sum to check if the transmission is made prop-erly will be found by doing XOR data from A to C.a) Type of data receivedb) Number of data (N+1) received after.----------c) DATA(N)----------d) Check sum(1)start stopbit data 8bit (D0 ~ D7) bitD0 D1 D2 D3 D4 D5 D6 D7