畢業(yè)設(shè)計(jì)中英文資料--基于ch372實(shí)現(xiàn)can總線適配器-wenkub
2023-01-28 06:35:26 本頁(yè)面
【正文】 the write order port of CH372 could be defined as 0xBD00,and the I/O addresses on the read and write data port could be defined as 0xBC00. When WR is on high level and CS,RD and A0 are on low level, the data in CH372 output through D0D7, and when RD is on high level and CS, WR and A0 are on low level, the data are written in CH372 through D0D7, and when RD is on high level and CS and WR are on low level and A0 is on high level, the orders are written in CH372 through internally installs power supply POR, so it generally needs not reset from the exterior. CH372 needs 12MHz clock signal supplied by the exterior when it works normally. The clock signals are produced by the inverter internally installed in CH372 through crystal stabilized oscillator. The surrounding circuit only needs to connect a crystal with standard frequency of 12MHz between and XO, and the pin XI and pin XO respectively connect with a high frequency oscillator capacitance. CH372 supports 5V power supply voltage or power supply voltage. When it works on 5V voltage, VCC pin of CH372 inputs exterior 5V power supply, and the V3 pin should exteriorly connect with the decoupling capacitance of about . When it works on 3V voltage, V3 pin of CH372 should connect with VCC pin, and input exterior power supply, and the work voltage of other circuits connected with CH372 should not exceed . Hardware design of CAN munication module The hardware circuit of CAN bus munication module adopts CAN bus control chip SJA1000, bus driver PCA82C250 and highspeed photocouplers 6N137. The SCM AT89C51 pletes the initialization of SJA1000, and implements the transmission and acceptance of data through controlling SJA1000. CAN controller adopt SJA1000 made by PHILIPS, and it could work on BasicCAN mode or PeliCAN mode. The maximum bit speed could achieve 1Mbit/s, and it supports Intel and Motorola microcontroller. SCM could interview SJA1000 through the mode to interview exterior , RD and ALE of SJA1000 respectively connect with WR and RD of SCM. The pin INT of SJA1000 connects with INT1 of SCM. The patch selection port of SJA1000 connects with of CSM, and the low level is effective, and its initial address is defined as 0xBB00. TX0 and RX0 of SJA1000 connect with CAN bus transceiver PCA82C250 through highspeed lightcoupler insulation 6N137. To avoid the collision of over current, CANH and CANL of PCA82C250 respectively connect with CAN bus through 5Ω current limited resistance. CANH and CANL parallel connect two 30pF capacitances with earth, which could eliminate the high frequency interference and prevent certain electromagic radiation on the bus. 3. The implementation of
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