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Discussion Groups | M68HC11 | How can I connect PC to HC11 through RS232?
Technical discussions about Freescale Microcontrollers: M68HC11. (Freescale Semiconductor is a Subsidiary of Motorola).
How can I connect PC to HC11 through RS232? - Alexey Londkevich - Nov 18 15:59:00 2004
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Hello, all. I am beginner in 68hc11 progamming. I must make some changes for same program. I want to write small debug program for debugging through serial connection. I connect PC directly to 68hc11. (Ground -ground, td-rd, rd-td). I trying send chars from 68hc11 to PS. It work. But I can not send char from PC. What do I wrongly? Perhaps it is no right - directly connection? |
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Re: How can I connect PC to HC11 through RS232? - quyenqtran - Nov 18 16:48:00 2004
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You just can't connect directly to the PC from the HC11. You need to go thru the RS232. You also need a pull up resistor for the TxD pin of the HC11. What I usually do is I also used a Sub-D9 connector to connect to the Serial port of the PC. -Quyen --- In , Alexey Londkevich <lond@u...> wrote: > Hello, all. > > I am beginner in 68hc11 progamming. > I must make some changes for same program. > I want to write small debug program for debugging through serial connection. > I connect PC directly to 68hc11. (Ground -ground, td-rd, rd-td). > I trying send chars from 68hc11 to PS. It work. > But I can not send char from PC. > What do I wrongly? > Perhaps it is no right - directly connection? |
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Re: How can I connect PC to HC11 through RS232? - bart homerson - Nov 18 17:52:00 2004
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Hello, You must use a Rs-232 transciver chip such as the MAX232. What this chip does is it translates the voltages from the RX side of the RS232 protocol into Logic-level (+5V) for the MCU to understand. It then translates the TX pin voltage from logic-level to the necessary -13 to 0 voltage level to match the RS232 protocol. It's a bit confusing, but once you get it, you wont forget it. I suggest doing a Google search for "RS-232 protocol" you will find a bunch of information. I hope this answer was along the lines of what you are looking for. RS-232 is a wonderful protocol with a lot of potential. Take care. LF Alexey Londkevich <> wrote: Hello, all. I am beginner in 68hc11 progamming. I must make some changes for same program. I want to write small debug program for debugging through serial connection. I connect PC directly to 68hc11. (Ground -ground, td-rd, rd-td). I trying send chars from 68hc11 to PS. It work. But I can not send char from PC. What do I wrongly? Perhaps it is no right - directly connection? Yahoo! Groups SponsorADVERTISEMENT --------------------------------- Yahoo! Groups Links To --------------------------------- |
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Re: How can I connect PC to HC11 through RS232? - Scott Grodevant - Nov 19 8:52:00 2004
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Hi all and LF, You are close, but the RS-232 signaling levels are -15 to -5 (low state) and +5 to +15 for a high. Scott bart homerson <> wrote: Hello, You must use a Rs-232 transciver chip such as the MAX232. What this chip does is it translates the voltages from the RX side of the RS232 protocol into Logic-level (+5V) for the MCU to understand. It then translates the TX pin voltage from logic-level to the necessary -13 to 0 voltage level to match the RS232 protocol. It's a bit confusing, but once you get it, you wont forget it. I suggest doing a Google search for "RS-232 protocol" you will find a bunch of information. I hope this answer was along the lines of what you are looking for. RS-232 is a wonderful protocol with a lot of potential. Take care. LF Alexey Londkevich wrote: Hello, all. I am beginner in 68hc11 progamming. I must make some changes for same program. I want to write small debug program for debugging through serial connection. I connect PC directly to 68hc11. (Ground -ground, td-rd, rd-td). I trying send chars from 68hc11 to PS. It work. But I can not send char from PC. What do I wrongly? Perhaps it is no right - directly connection? Yahoo! Groups SponsorADVERTISEMENT --------------------------------- Yahoo! Groups Links To --------------------------------- Yahoo! Groups Links --------------------------------- |
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Re: How can I connect PC to HC11 through RS232? - bart homerson - Nov 19 11:50:00 2004
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Hello scott, Actually, the standard says that the voltage can be between +25 and -25. We're both incorrect. Thanks for making me look it up, my memory often fails me. Quoted from http://www.camiresearch.com/Data_Com_Basics/RS232_standard.html Signal State Voltage Assignments - Voltages of -3v to -25v with respect to signal ground (pin 7) are considered logic '1' (the marking condition), whereas voltages of +3v to +25v are considered logic '0' (the spacing condition). The range of voltages between -3v and +3v is considered a transition region for which a signal state is not assigned. I commonly see -13V, but rarely see anything over +5V on the oscilloscope with my configuration. LF Scott Grodevant <> wrote: Hi all and LF, You are close, but the RS-232 signaling levels are -15 to -5 (low state) and +5 to +15 for a high. Scott bart homerson wrote: Hello, You must use a Rs-232 transciver chip such as the MAX232. What this chip does is it translates the voltages from the RX side of the RS232 protocol into Logic-level (+5V) for the MCU to understand. It then translates the TX pin voltage from logic-level to the necessary -13 to 0 voltage level to match the RS232 protocol. It's a bit confusing, but once you get it, you wont forget it. I suggest doing a Google search for "RS-232 protocol" you will find a bunch of information. I hope this answer was along the lines of what you are looking for. RS-232 is a wonderful protocol with a lot of potential. Take care. LF Alexey Londkevich wrote: Hello, all. I am beginner in 68hc11 progamming. I must make some changes for same program. I want to write small debug program for debugging through serial connection. I connect PC directly to 68hc11. (Ground -ground, td-rd, rd-td). I trying send chars from 68hc11 to PS. It work. But I can not send char from PC. What do I wrongly? Perhaps it is no right - directly connection? Yahoo! Groups SponsorADVERTISEMENT --------------------------------- Yahoo! Groups Links To --------------------------------- Yahoo! Groups Links --------------------------------- Yahoo! Groups Links --------------------------------- |
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Re: How can I connect PC to HC11 through RS232? - Scott Grodevant - Nov 19 13:46:00 2004
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Hi all and LF, Thanks, my memory must be slipping too. Scott bart homerson <> wrote: Hello scott, Actually, the standard says that the voltage can be between +25 and -25. We're both incorrect. Thanks for making me look it up, my memory often fails me. Quoted from http://www.camiresearch.com/Data_Com_Basics/RS232_standard.html Signal State Voltage Assignments - Voltages of -3v to -25v with respect to signal ground (pin 7) are considered logic '1' (the marking condition), whereas voltages of +3v to +25v are considered logic '0' (the spacing condition). The range of voltages between -3v and +3v is considered a transition region for which a signal state is not assigned. I commonly see -13V, but rarely see anything over +5V on the oscilloscope with my configuration. LF Scott Grodevant wrote: Hi all and LF, You are close, but the RS-232 signaling levels are -15 to -5 (low state) and +5 to +15 for a high. Scott bart homerson wrote: Hello, You must use a Rs-232 transciver chip such as the MAX232. What this chip does is it translates the voltages from the RX side of the RS232 protocol into Logic-level (+5V) for the MCU to understand. It then translates the TX pin voltage from logic-level to the necessary -13 to 0 voltage level to match the RS232 protocol. It's a bit confusing, but once you get it, you wont forget it. I suggest doing a Google search for "RS-232 protocol" you will find a bunch of information. I hope this answer was along the lines of what you are looking for. RS-232 is a wonderful protocol with a lot of potential. Take care. LF Alexey Londkevich wrote: Hello, all. I am beginner in 68hc11 progamming. I must make some changes for same program. I want to write small debug program for debugging through serial connection. I connect PC directly to 68hc11. (Ground -ground, td-rd, rd-td). I trying send chars from 68hc11 to PS. It work. But I can not send char from PC. What do I wrongly? Perhaps it is no right - directly connection? Yahoo! Groups SponsorADVERTISEMENT --------------------------------- Yahoo! Groups Links To --------------------------------- Yahoo! Groups Links --------------------------------- Yahoo! Groups Links --------------------------------- Yahoo! Groups Links --------------------------------- |
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Re: How can I connect PC to HC11 through RS232? - Alexey Londkevich - Nov 19 16:05:00 2004
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Thanx, people for explainig and links. Will to try MAX 232 |
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Re: How can I connect PC to HC11 through RS232? - bart homerson - Nov 19 16:31:00 2004
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lol LF Scott Grodevant <> wrote: Hi all and LF, Thanks, my memory must be slipping too. Scott bart homerson wrote: Hello scott, Actually, the standard says that the voltage can be between +25 and -25. We're both incorrect. Thanks for making me look it up, my memory often fails me. Quoted from http://www.camiresearch.com/Data_Com_Basics/RS232_standard.html Signal State Voltage Assignments - Voltages of -3v to -25v with respect to signal ground (pin 7) are considered logic '1' (the marking condition), whereas voltages of +3v to +25v are considered logic '0' (the spacing condition). The range of voltages between -3v and +3v is considered a transition region for which a signal state is not assigned. I commonly see -13V, but rarely see anything over +5V on the oscilloscope with my configuration. LF Scott Grodevant wrote: Hi all and LF, You are close, but the RS-232 signaling levels are -15 to -5 (low state) and +5 to +15 for a high. Scott bart homerson wrote: Hello, You must use a Rs-232 transciver chip such as the MAX232. What this chip does is it translates the voltages from the RX side of the RS232 protocol into Logic-level (+5V) for the MCU to understand. It then translates the TX pin voltage from logic-level to the necessary -13 to 0 voltage level to match the RS232 protocol. It's a bit confusing, but once you get it, you wont forget it. I suggest doing a Google search for "RS-232 protocol" you will find a bunch of information. I hope this answer was along the lines of what you are looking for. RS-232 is a wonderful protocol with a lot of potential. Take care. LF Alexey Londkevich wrote: Hello, all. I am beginner in 68hc11 progamming. I must make some changes for same program. I want to write small debug program for debugging through serial connection. I connect PC directly to 68hc11. (Ground -ground, td-rd, rd-td). I trying send chars from 68hc11 to PS. It work. But I can not send char from PC. What do I wrongly? Perhaps it is no right - directly connection? Yahoo! Groups SponsorADVERTISEMENT --------------------------------- Yahoo! Groups Links To --------------------------------- ">http://mail.yahoo.com [Non-text portions of this message have been removed] |
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Re: Re: How can I connect PC to HC11 through RS232? - bart homerson - Nov 19 16:39:00 2004
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If you are going to use the MAX 232, then you will need to order some capacitors too.
There are RS232 chips that do not require them; the MAX232 was the first chip that came to
my mind. I would suggest that you look through the data sheets of the various chips before
you actually make a decision. Digikey, http://www.digikey.com, has 1284 different RS232
devices they also usually have a good number of data sheets for the chips they stock. Good
luck. LF Alexey Londkevich <> wrote: Thanx, people for explainig and links. Will to try MAX 232 Yahoo! Groups Sponsor Get unlimited calls to U.S./Canada --------------------------------- Yahoo! Groups Links To --------------------------------- |
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Re: Re: How can I connect PC to HC11 through RS232? - Alexey Londkevich - Nov 19 16:43:00 2004
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Thanx, I will to study this site On Friday 19 of November 2004 22:39, bart homerson wrote: > If you are going to use the MAX 232, then you will need to order some > capacitors too. There are RS232 chips that do not require them; the MAX232 > was the first chip that came to my mind. I would suggest that you look > through the data sheets of the various chips before you actually make a > decision. Digikey, http://www.digikey.com, has 1284 different RS232 > devices they also usually have a good number of data sheets for the chips > they stock. Good luck. > > LF > > Alexey Londkevich <> wrote: > Thanx, people for explainig and links. > Will to try MAX 232 > > Yahoo! Groups Sponsor > Get unlimited calls to > > U.S./Canada > --------------------------------- > Yahoo! Groups Links > > To > > --------------------------------- > > Yahoo! Groups Links > |
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