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I am concerned about bar code interface with LPC1768/LPC1769 controller.. If I use only UART-TX, UART-RX, GND pin of controller only to interface with barcode scanner module which has UART or RS232 option( without mapping handshaking signal), i) is it possible to communicate with barcode device. ii) What should I do with RTS/CTS if they are not used.

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  • \$\begingroup\$ To answer that we need to know a lot more about the whole environment. You need to check the specification of the scanner. How fast can it send/receive. Does it support XON-XOFF. What is it connected to (probably a computer). How fast is that computer, how long does it take to process one scan code etc. etc. \$\endgroup\$ – Oldfart Aug 10 '18 at 7:11
  • \$\begingroup\$ Ok thanks for reply. My query is , if assumed data rate is not issue to LPC1768 and barcode, what pin status is required for CTS, RTS pin of controller LPC1768 to establish connection with barcode. \$\endgroup\$ – Techknowlogic Aug 10 '18 at 7:27
  • \$\begingroup\$ Add that to the question. Your actual question is: What should I do with RTS/CTS if they are not used. \$\endgroup\$ – Oldfart Aug 10 '18 at 7:29
  • \$\begingroup\$ Most modern RS-232 implementations run at speeds that are well within the range that modern devices and controllers can handle without handshaking (HW or SW) if they are not under heavy load. You would traditionally connect HW handshake inputs to asserted outputs from one of the devices if you are not using them. The exact useage of the handshake has been rather implementation specific because the standard was developed for slow modems and faster computers a long time ago, the handshake is traditionally there to pause the computer but these days it is often to pause the device. \$\endgroup\$ – KalleMP Aug 10 '18 at 7:37
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Most barcode readers can be configured to send automatically, so you will only need the RX pin on your microcontroller.

The unused barcode reader input pins should be tied to voltages that indicate a ready state. (on rs232 this was high, so on a UART it would be low (grond)) unused outputs should be left unconnected.

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