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Discussion Groups | BasicX | RS232 interface?
Discussion forum for the BasicX family of microcontroller chips.
RS232 interface? - tan_teckchoon - Sep 27 23:21:00 2002
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Hi guy, Pls advise the following: a) According to BX-24 documentation, we can communciate with external devices using RS232 (COM1 or COM3) port through SerialPort command with CallQueue and OpenQueue. In additional, there is also a sample source code, SerialPort.bas, in the documentation, however there is not description on which pins of RS232 should be connected to BX-24. Hence, appreciate if you can kindly advise the connections for getting String and Unsigned Integer Input/Output through RS232. b) Can we actually connect RS232 directly to I/O pins of BX-24, as I understand that RS232 would have a voltage of 12V whilst BX-24 I/O pins are rated at 5V? Thks alot |
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Re: RS232 interface? - Tony Brenke - Sep 28 2:17:00 2002
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--- tan_teckchoon <> wrote: > Hi guy, > > Pls advise the following: > > a) According to BX-24 documentation, we can communciate with > external devices using RS232 (COM1 or COM3) port through SerialPort > command with CallQueue and OpenQueue. In additional, there is also a > sample source code, SerialPort.bas, in the documentation, however > there is not description on which pins of RS232 should be connected > to BX-24. Hence, appreciate if you can kindly advise the connections > for getting String and Unsigned Integer Input/Output through RS232. use the serialport.bas in the examples section. > > b) Can we actually connect RS232 directly to I/O pins of BX-24, as > I understand that RS232 would have a voltage of 12V whilst BX-24 I/O > pins are rated at 5V? NO, you will fry the BX. use a max233 (no ext parts) or a max233 (external parts required) > Thks alot > __________________________________________________ |
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Re: RS232 interface? - Gregg Martell - Sep 28 10:21:00 2002
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Generally, you'll need a convertor to take the BX pins from TTL to RS-232. A MAX232 chip can do this with a few extra components (capacitors) and 5V power. Some devices do have TTL (5V) serial connections. Gregg At 04:21 AM 9/28/02 +0000, you wrote: >Hi guy, > >Pls advise the following: > >a) According to BX-24 documentation, we can communciate with >external devices using RS232 (COM1 or COM3) port through SerialPort >command with CallQueue and OpenQueue. In additional, there is also a >sample source code, SerialPort.bas, in the documentation, however >there is not description on which pins of RS232 should be connected >to BX-24. Hence, appreciate if you can kindly advise the connections >for getting String and Unsigned Integer Input/Output through RS232. > >b) Can we actually connect RS232 directly to I/O pins of BX-24, as >I understand that RS232 would have a voltage of 12V whilst BX-24 I/O >pins are rated at 5V? >Thks alot |
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Re: RS232 interface? - Frank Manning - Sep 28 13:05:00 2002
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From: "Tony Brenke" <> > --- tan_teckchoon <> wrote: > >> [...] >> b) Can we actually connect RS232 directly to I/O pins of >> BX-24, as I understand that RS232 would have a voltage of >> 12V whilst BX-24 I/O pins are rated at 5V? > > NO, you will fry the BX. [...] For a BX-01 and BX-35, this is true. You shouldn't connect an RS-232 line directly to the AVR chip without going through a hardware interface. A BX-24 already includes an interface, though. You can connect directly to an RS-232 line. Disclaimer -- I'm by no means a hardware expert, so I'm walking on very thin ice when I start expounding on hardware. I welcome any corrections. -- Frank Manning -- NetMedia, Inc. |
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Re: RS232 interface? - Bruce J. Weimer, MD - Sep 28 13:25:00 2002
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tan_teckchoon <> wrote: Can we actually connect RS232 directly to I/O pins of BX-24, as I understand that RS232 would have a voltage of 12V whilst BX-24 I/O pins are rated at 5V? Tony Brenke wrote: NO, you will fry the BX. use a max233 (no ext parts) or a max233 (external parts required) And Bruce Weimer asks: True, except that we connect the PC's serial port directly to the BX24's com1 port every time we download a program - isn't that RS232? Why doesn't the PC fry the BX24? [Non-text portions of this message have been removed] |
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Servo Power Problem - David E. Basile - Sep 28 13:28:00 2002
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A was wondering if some one might be able to help me with a small servo problem I'm having. I have a 5 volt power supply feeding my servo with common grounds. During my project I'm building the code in modules and tested the servo for movement and it works fine. When I left everything hooked up and started testing another part of my project (PWM) I notice the servo gets HOT. VERY Hot! During the servo test it doesn't. I'm using Pin 7 for the servo control and my other code module uses totally different pins so I'm pretty sure that's not the problem. When I run the test code for a bit the servo does not get hot so I'm guessing it has to do with the level of the control pin when it is not active in my other module. Also I'm using a small 5 volt power supply and not a battery. Can any body tell me what I'm doing wrong? TIA David [Non-text portions of this message have been removed] |
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Re: RS232 interface? - Bruce J. Weimer, MD - Sep 28 13:30:00 2002
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Frank Manning wrote: For a BX-01 and BX-35, this is true. You shouldn't connect an RS-232 line directly to the AVR chip without going through a hardware interface. A BX-24 already includes an interface, though. You can connect directly to an RS-232 line. Disclaimer -- I'm by no means a hardware expert, so I'm walking on very thin ice when I start expounding on hardware. I welcome any corrections. Bruce Weimer writes: Thanks Frank! You actually answered my question literally as I was pushing the "send" button to send it - you must have been reading my mind!! Bruce. [Non-text portions of this message have been removed] |
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Re: Servo Power Problem - Tony Brenke - Sep 28 21:56:00 2002
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your servo pin is output at 5V. that is overdriving your servo causing the heat. --- "David E. Basile" <> wrote: > A was wondering if some one might be able to help me with a small servo > problem I'm having. I have a 5 volt power supply feeding my servo with > common grounds. During my project I'm building the code in modules and > tested the servo for movement and it works fine. When I left everything > hooked up and started testing another part of my project (PWM) I notice the > servo gets HOT. VERY Hot! During the servo test it doesn't. I'm using Pin > 7 for the servo control and my other code module uses totally different pins > so I'm pretty sure that's not the problem. > > When I run the test code for a bit the servo does not get hot so I'm > guessing it has to do with the level of the control pin when it is not > active in my other module. Also I'm using a small 5 volt power supply and > not a battery. > > Can any body tell me what I'm doing wrong? > > TIA > David > [Non-text portions of this message have been removed] > __________________________________________________ |
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Re: RS232 interface? - Tony Brenke - Sep 28 21:58:00 2002
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true you can connect directly to the bx-24 pins. BUT only these. Pin 2 = TX >--------< Pin 1 of the BX-24 Pin 3 = RX >--------< Pin 2 of the BX-24 Pin 4 = ATN >--------< Pin 3 of the BX-24 Pin 5 = Ground >--------< Pins 4 or 23 of the BX-24 --- "Bruce J. Weimer, MD" <> wrote: > tan_teckchoon <> wrote: > > Can we actually connect RS232 directly to I/O pins of BX-24, as > I understand that RS232 would have a voltage of 12V whilst BX-24 I/O > pins are rated at 5V? > > > Tony Brenke wrote: > > NO, you will fry the BX. > use a max233 (no ext parts) or a max233 (external parts required) > And Bruce Weimer asks: > > True, except that we connect the PC's serial port directly to the BX24's com1 port every time we > download a program - isn't that RS232? Why doesn't the PC fry the BX24? > > [Non-text portions of this message have been removed] > __________________________________________________ |
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Re: RS232 interface? - tan_teckchoon - Sep 29 3:38:00 2002
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Thanks for all the kind reply. Please kindly advise the function of max233? By the way, have anyone tried SerialPort.bas program before, any idea regarding its connection? teck choon --- In basicx@y..., "Bruce J. Weimer, MD" <weimer@m...> wrote: > tan_teckchoon <tan_teckchoon@y...> wrote: > > Can we actually connect RS232 directly to I/O pins of BX-24, as > I understand that RS232 would have a voltage of 12V whilst BX-24 I/O > pins are rated at 5V? > > > Tony Brenke wrote: > > NO, you will fry the BX. > use a max233 (no ext parts) or a max233 (external parts required) > And Bruce Weimer asks: > > True, except that we connect the PC's serial port directly to the BX24's com1 port every time we download a program - isn't that RS232? Why doesn't the PC fry the BX24? > > [Non-text portions of this message have been removed] |
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Re: Re: RS232 interface? - Gregg Martell - Sep 29 8:05:00 2002
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http://chaokhun.kmitl.ac.th/~kswichit/MAX232/MAX232.htm http://dbserv.maxim-ic.com/quick_view2.cfm?pdf_num=1798 At 08:38 AM 9/29/02 +0000, you wrote: >Thanks for all the kind reply. > >Please kindly advise the function of max233? By the way, have anyone >tried SerialPort.bas program before, any idea regarding its >connection? > >teck choon >--- In basicx@y..., "Bruce J. Weimer, MD" <weimer@m...> wrote: > > tan_teckchoon <tan_teckchoon@y...> wrote: > > > > Can we actually connect RS232 directly to I/O pins of BX-24, as > > I understand that RS232 would have a voltage of 12V whilst BX-24 >I/O > > pins are rated at 5V? > > > > > > > > > > Tony Brenke wrote: > > > > NO, you will fry the BX. > > use a max233 (no ext parts) or a max233 (external parts required) > > > > > > And Bruce Weimer asks: > > > > True, except that we connect the PC's serial port directly to the >BX24's com1 port every time we download a program - isn't that >RS232? Why doesn't the PC fry the BX24? > > > > [Non-text portions of this message have been removed] |
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Re: RS232 interface? - Frank Manning - Sep 29 14:46:00 2002
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From: "Tony Brenke" <> > true you can connect directly to the bx-24 pins. > BUT only these. > > Pin 2 = TX >--------< Pin 1 of the BX-24 > Pin 3 = RX >--------< Pin 2 of the BX-24 > Pin 4 = ATN >--------< Pin 3 of the BX-24 > Pin 5 = Ground >--------< Pins 4 or 23 of the BX-24 Yes, good point. This is Com1, which doesn't require additional hardware. By contrast, Com3 does require additional hardware for an RS-232 connection. The original message asked about both Com1 and Com3, so it's important to make that distinction. -- Frank Manning -- NetMedia, Inc. |
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Re: RS232 interface? - Vince Pearman - Sep 30 7:58:00 2002
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All, I have been reading GPS data from a Garmin eTrex on com3 / pin 6 using straight RS-232 level signals for a while now, without a glitch. Have I just been extremely lucky that I haven't fried anything? ----- Original Message ----- > From: "Tony Brenke" <> > > > true you can connect directly to the bx-24 pins. > > BUT only these. > > > > Pin 2 = TX >--------< Pin 1 of the BX-24 > > Pin 3 = RX >--------< Pin 2 of the BX-24 > > Pin 4 = ATN >--------< Pin 3 of the BX-24 > > Pin 5 = Ground >--------< Pins 4 or 23 of the BX-24 > > Yes, good point. This is Com1, which doesn't require additional > hardware. By contrast, Com3 does require additional hardware for > an RS-232 connection. > > The original message asked about both Com1 and Com3, so it's > important to make that distinction. > > -- Frank Manning > -- NetMedia, Inc. |
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RE: RS232 interface? - Harry J. White - Sep 30 8:04:00 2002
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Possibly. Some implementations of RS-232 use (0 and 5) volts instead of +-12. It's somewhat of a cheat on the part of the manufacturer but they still do it. I have a Model 100 laptop computer from Radio Shack that uses 0 and 5 volts. Check the comm specks on your GPS. -----Original Message----- From: Vince Pearman [mailto:] Sent: Monday, September 30, 2002 8:58 AM To: Subject: Re: [BasicX] RS232 interface? All, I have been reading GPS data from a Garmin eTrex on com3 / pin 6 using straight RS-232 level signals for a while now, without a glitch. Have I just been extremely lucky that I haven't fried anything? ----- Original Message ----- > From: "Tony Brenke" <> > > > true you can connect directly to the bx-24 pins. > > BUT only these. > > > > Pin 2 = TX >--------< Pin 1 of the BX-24 > > Pin 3 = RX >--------< Pin 2 of the BX-24 > > Pin 4 = ATN >--------< Pin 3 of the BX-24 > > Pin 5 = Ground >--------< Pins 4 or 23 of the BX-24 > > Yes, good point. This is Com1, which doesn't require additional > hardware. By contrast, Com3 does require additional hardware for > an RS-232 connection. > > The original message asked about both Com1 and Com3, so it's > important to make that distinction. > > -- Frank Manning > -- NetMedia, Inc. [Non-text portions of this message have been removed] |
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