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learn:fundamentals:communication-protocols:uart:start [2016/07/11 20:47] – created Sam Klearn:fundamentals:communication-protocols:uart:start [2022/10/04 11:38] (current) – external edit 127.0.0.1
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-In terms of communicating with a host board, there are two required signal lines with up to four total signal lines that are available. The two required lines are the TXD (transmit data) and RXD (receive data). The remaining two signal lines available are the RTS (ready to send) and CTS (clear to send). These two signals, if used, are commonly asserted independently by the two devices that are communicating. One device with raise (bring to a high voltage state) its RTS line and "listen" on the CTS line. The second device, once ready, will raise its RTS line, which will be detected on the first device's CTS line, and listen for the raised RTS signal from the first device on its own CTS line. Once both devices have indicated that they are ready, data transmission can occur.+In terms of communicating with a host board, there are two required signal lines with up to four total signal lines that are available. The two required lines are the TXD (transmit data) and RXD (receive data). The remaining two signal lines available are the RTS (ready to send) and CTS (clear to send). These two signals, if used, are commonly asserted independently by the two devices that are communicating. One device will lower (bring to a low voltage state) its RTS line and "listen" on the CTS line. The second device, once ready, will lower its RTS line, which will be detected on the first device's CTS line, and listen for the lowered RTS signal from the first device on its own CTS line. Once both devices have indicated that they are ready, data transmission can occur.
  
-However, the RTS and CTS lines are not required to be connected; when left floating, both of these lines are at a high voltage state, essentially indicating that both devices are ready to communicate with one another through the RXD and TXD lines. Since a "start bit" is always sent first, this incoming transition can easily be detected by the system board, triggering an interrupt signal to indicate that there is incoming data.+However, the RTS and CTS lines are not required to be connected. When flow control is disabled, these pins will be ignored altogether. Since a "start bit" is always sent first, this incoming transition can easily be detected by the system board, triggering an interrupt signal to indicate that there is incoming data.
  
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