![\"\"](\"https:\/\/blog.seeedstudio.com\/wp-content\/uploads\/2020\/09\/ch340g1.jpg\")
In the serial port mode, CH340 provides\ncommonly used MODEM contact signals, which are used to expand asynchronous\nserial ports for computers, or to directly upgrade common serial devices to USB\nbus.<\/p>\n\n\n\n
In infrared mode, CH340 can form a USB infrared adapter by adding an infrared transceiver to realize SIR infrared communication.<\/p>\n\n\n\n
Why use CH340?<\/h2>\n\n\n\n
Both the serial port and the CH340 module can allow the computer to communicate with the single-chip computer, but it is more convenient to use the CH340, which saves the trouble of using the serial port.<\/p>\n\n\n\n
Features of ch340<\/h2>\n\n\n\n
It has a full-speed USB device interface and is compatible with USBV2.0. It is simple to use, and the peripheral components only need crystals and capacitors.<\/p>\n\n\n\n
Emulate the standard serial port, used to upgrade the original serial peripheral device, or add additional serial ports via USB.<\/p>\n\n\n\n
It is compatible with the serial port application USBV2.0 under the computer’s Windows operating system, so no modification is required.<\/p>\n\n\n\n
It supports commonly used MODEM contact signals, including RTS, DTR, DCD, RI, DSR, CTS, etc.<\/p>\n\n\n\n
It can provide RS232, RS485, RS422 and other interfaces through external level conversion equipment.<\/p>\n\n\n\n
It significantly supports IrDA standard SIR infrared communication, while supporting baud rates from 2400bps to 115200bps.<\/p>\n\n\n\n
Because it is a serial port converted by USB, it can only be compatible at the application layer, and cannot be absolutely the same.<\/p>\n\n\n\n
The software is compatible with CH341, which can directly use the driver of CH341.<\/p>\n\n\n\n
Support 5V voltage and 3.3V voltage.<\/p>\n\n\n\n
It is compatible with RoHS.<\/p>\n\n\n\n
the package of ch340<\/h2>\n\n\n\n
CH340 has a variety of packaging methods, including CH340R, CH340T, CH340G. Each packaging method is slightly different, and its functions are also different. <\/p>\n\n\n\n CH340T:\n<\/strong>Under the Windows operating system on the computer\nside, the driver of CH340T can emulate a standard serial port and can perform\nserial port operations. It is fully compatible with most of the original serial\nport applications and usually does not require any modification. CH340T can be\nused to upgrade the original serial peripheral equipment, or to add additional\nserial ports to the computer through the USB bus. By adding level conversion\ndevices, it can further provide RS232, RS485, RS422 and other interfaces.<\/p>\n\n\n\n CH340R:<\/strong> CH340R provides a 9-wire serial port with reverse polarity and\nsupports IrDA. But it has no built-in crystal oscillator.<\/p>\n\n\n\n CH340G<\/strong>\uff1aCH340G provides a full 9-wire serial port without a built-in crystal oscillator.<\/p>\n\n\n\n Pin 1\uff1aThe common terminal\nis grounded and directly connected to the ground wire of the USB bus.<\/p>\n\n\n\n Pin 2\uff1aSerial data output.<\/p>\n\n\n\n Pin 3\uff1aSerial data input,\nbuilt-in controllable pull-up and pull-down resistors.<\/p>\n\n\n\n Pin 4\uff1aWhen the power\nsupply voltage is 3.3V, connect VCC to input external power;<\/p>\n\n\n\n When the power supply voltage is 5V, an\nexternal decoupling capacitor with a capacity of 0.1uF;<\/p>\n\n\n\n Pin 5\uff1aThis pin is directly\nconnected to the USB D+ data line.<\/p>\n\n\n\n Pin 6\uff1aThis pin is directly\nconnected to the D-data line of the USB.<\/p>\n\n\n\n Pin 7\uff1aThis pin is the\ninput terminal for crystal oscillation, which requires an external crystal and\ncapacitor.<\/p>\n\n\n\n Pin 8\uff1aThis pin is the\noutput terminal of the crystal oscillator, which requires an external crystal\nand capacitor.<\/p>\n\n\n\n Pin 9\uff1aMODEM contact input\nsignal, clear to send, low (high) effective.<\/p>\n\n\n\n Pin 10\uff1aMODEM contact input\nsignal, data device is ready, low (high) effective.<\/p>\n\n\n\n Pin 11\uff1aMODEM contact input\nsignal, ringing indicator, low (high) effective.<\/p>\n\n\n\n Pin 12\uff1aMODEM contact input\nsignal, carrier detection, low (high) effective.<\/p>\n\n\n\n Pin 13\uff1aMODEM contact output\nsignal, data terminal is ready, low (high) effective.<\/p>\n\n\n\n Pin 14\uff1aMODEM contact output\nsignal, request to send, low (high) effective.<\/p>\n\n\n\n Pin 15\uff1aAuxiliary RS232\nenable, high level effective, built-in pull-down resistor.<\/p>\n\n\n\n Pin 16\uff1aThe positive power input terminal requires an external 0.1uF power decoupling capacitor.<\/p>\n\n\n\n The TXD pin of H340 should be connected to\nthe RXD pin of the microcontroller, and the RXD pin should be connected to the\nTXD pin of the microcontroller.<\/p>\n\n\n\n In addition, connecting a diode at the TXD\npin and a resistor at RXD are both to prevent the USB from supplying power to\nthe target chip.<\/p>\n\n\n\n In the above picture, a toggle switch is used to control the power supply of the microcontroller, so that the power supply can be disconnected when unnecessary.<\/p>\n\n\n\n 1. CH340 has a built-in power-on reset circuit. 2. The CH340 chip needs to provide a 12MHz\nclock signal to the XI pin when it works normally. Generally, the built-in\ninverter of CH340 can generate clock signal through stable oscillation of\ncrystal frequency. The peripheral circuit only needs to connect a 12MHz crystal\nbetween the XI and XO pins, and connect the XI and XO pins to the ground\nrespectively with an oscillation capacitor.<\/p>\n\n\n\n 3. CH340 chip supports 5V DC voltage or\n3.3V DC voltage. When using 5V power supply, the VCC pin of the CH340 chip is\nconnected to an external 5V power supply. At this time, the V3 pin should be\nconnected to an external power supply decoupling capacitor with a capacity of\n4700pF or 0.01uF. When using 3.3V power supply, the V3 pin of the CH340 chip\nshould be connected to the VCC pin, and the external 3.3V power supply of\n4700pFnd should be input at the same time, and the working voltage of other\ncircuits connected to the CH340 chip cannot exceed 3.3V.<\/p>\n\n\n\n 4. CH340 automatically supports USB device\nsuspension to save power consumption. However, when the NOS# pin is low, the\nUSB device is prohibited from suspending. In asynchronous serial port mode, the\npins of the CH340 chip include: data transmission pins, MODEM contact signal\npins and auxiliary pins. The data transmission pins include: TXD pin and RXD\npin. If the R232 pin is high to enable the auxiliary RS232 function, the\ninverter will automatically insert the RXD pin, which is low by default.<\/p>\n\n\n\n 5. MODEM contact signal pins include: CTS#\npin, DSR# pin, RI# pin, DCD# pin, DTR# pin, RTS# pin. All these MODEM\ncommunication signals are controlled by computer applications and define their\nuses.<\/p>\n\n\n\n 6. IR# pin is low to enable infrared serial\nport mode. When R232 is high, the RXD pin input is automatically reversed. The\nACT# pin is the status output of the USB device configuration completion (for\nexample, the USB infrared adapter is ready). IR# and R232 pins are checked only\nonce after power-on reset.<\/p>\n\n\n\n 7. Serial data includes 1 low-level start\nbit, 5, 6, 7 or 8 data bits, 1 or 2 high-level stop bits, and supports\nodd\/even\/mark\/blank check Test. The baud rate error of the serial port sending\nsignal is less than 0.3%, and the allowable baud rate error of the serial port\nreceiving signal is not less than 2%.<\/p>\n\n\n\n 8. Under the Windows operating system on\nthe computer side, the CH340 driver can simulate a standard serial port, so\nunder normal circumstances, most of the original serial port applications are\ncompletely compatible.<\/p>\n\n\n\n 9. CH340 can be used to upgrade the\noriginal serial peripherals, or add additional serial ports to the computer\nthrough the USB bus. By adding level conversion devices, you can further\nprovide RS232, RS485, RS422 and other interfaces.<\/p>\n\n\n\n CH340G<\/a> is very important in PCB. Seeed Fusion<\/a> has a powerful component library, which can complete PCB assembly as quickly as possible.<\/p>\n","protected":false},"excerpt":{"rendered":" CH340 is a USB bus adapter chip. Its functions include USB to serial port and<\/p>\n","protected":false},"author":40,"featured_media":36435,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_lmt_disableupdate":"","_lmt_disable":"","_price":"","_stock":"","_tribe_ticket_header":"","_tribe_default_ticket_provider":"","_tribe_ticket_capacity":"0","_ticket_start_date":"","_ticket_end_date":"","_tribe_ticket_show_description":"","_tribe_ticket_show_not_going":false,"_tribe_ticket_use_global_stock":"","_tribe_ticket_global_stock_level":"","_global_stock_mode":"","_global_stock_cap":"","_tribe_rsvp_for_event":"","_tribe_ticket_going_count":"","_tribe_ticket_not_going_count":"","_tribe_tickets_list":"[]","_tribe_ticket_has_attendee_info_fields":false,"iawp_total_views":0,"footnotes":""},"categories":[1],"tags":[],"class_list":["post-36433","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news"],"yoast_head":"\n![\"\"](\"https:\/\/image.baidu.com\/search\/detail?ct=503316480&z=0&ipn=d&word=ch340&step_word=&hs=0&pn=23&spn=0&di=66220&pi=0&rn=1&tn=baiduimagedetail&is=0%2C0&istype=0&ie=utf-8&oe=utf-8&in=&cl=2&lm=-1&st=undefined&cs=883135506%2C2414575886&os=3522423099%2C3545797397&simid=4166091397%2C612040313&adpicid=0&lpn=0&ln=1146&fr=&fmq=1601209076038_R&fm=&ic=undefined&s=undefined&hd=undefined&latest=undefined©right=undefined&se=&sme=&tab=0&width=undefined&height=undefined&face=undefined&ist=&jit=&cg=&bdtype=0&oriquery=&objurl=http%3A%2F%2Fwww.xplian.net%2FtuxpJDEwLmFsaWNkbi5jb20vaTMvNDA4MjE1OTE5My9PMUNOMDEySG1SVWhQM1JCYlh0WDRfISE0MDgyMTU5MTkzJDk.jpg&fromurl=ippr_z2C%24qAzdH3FAzdH3Fooo_z%26e3Bxrstwg_z%26e3BgjpAzdH3FxrrcaaamcdnAzdH3Fc0b8cndnd9d8AzdH3F&gsm=18&rpstart=0&rpnum=0&islist=&querylist=&force=undefined\")
The pin function of CH340G<\/h2>\n\n\n\n
Schematic diagram of CH340 module circuit <\/h2>\n\n\n\n
Precautions:<\/h2>\n\n\n\n
<\/p>\n\n\n\n