these units powered by the signals on pins 7(RTS), 4(DTR), and 3(TD). These handshake lines can be in either the high or low condition, but *must be present* to power the converter.
If there is no adequate power, generating the necessary RS-232 voltage levels does not work. so... are RTS and DTR active? LP On Friday, June 20, 2014 9:00:41 PM UTC+2, Alvin M wrote: > > I added a 232PTTL33 converter and now communication to the beaglebone > works but communication from it to the computer doesn't work. The > converter definetly is an improvement but not a complete solution has > anyone else had good luck with it? > > On Thursday, June 19, 2014 4:06:05 PM UTC-4, PLyttle wrote: >> >> When you say that the gps works on your windows box, I assume it has an >> "com" interface, i.e. an RS-232 interface. >> The BBB does not use this specification. it uses a "3.3v ttl". serial >> connection. >> >> there are a few differences, >> a: the voltage levels. RS232 specs allow voltages at least -25 to +25 >> volt (common is -9 - +9 volts). BBB allows 0-3.3V >> b: the logic. a '1' on RS-232 is *minus* 3-25 volt. a '1' on BBB is >> *plus* 3.3 volt. >> >> Other things that can go wrong: >> a: Not using a common ground. i.e only connecting rx and tx and assuming >> the ground is good. >> b: Using the wrong frame. 8 or 7 databits, 1, 1.5 or 2 stop bits >> In all these cases a loopback will work, because the machine uses it's >> own specs. >> >> c; there are crappy RS-232 - "ttl" converters on the market. >> >> please look up the RS-232 spec, If you don't know what you are doing you >> can easily fry the BBB >> >> >> success, LP >> >> On Thursday, June 19, 2014 3:49:31 PM UTC+2, Alvin M wrote: >>> >>> I'm working on a custom linux distro for our customer product. I've got >>> a gps that works when I plug it into my windows machine but on linux at the >>> same baud rate I'm getting gabled output. I've tested it on loopback and it >>> seems to work fine for loopback other than some extra newlines. I had to >>> manually set the pins to >>> >>> name: uart1_txd.uart1_txd (0x44e10984/0x984 = 0x0040), b NA, t NA >>> mode: OMAP_MUX_MODE0 | AM33XX_SLEWCTRL_SLOW >>> signals: uart1_txd | mmc2_sdwp | NA | i2c1_scl | NA | pr1_uart0_txd_mux1 >>> | NA | gpio0_15 >>> >>> name: uart1_rxd.uart1_rxd (0x44e10980/0x980 = 0x0070), b NA, t NA >>> mode: OMAP_MUX_MODE0 | AM33XX_PIN_INPUT_PULLUP | AM33XX_SLEWCTRL_SLOW >>> signals: uart1_rxd | mmc1_sdwp | NA | i2c1_sda | NA | pr1_uart0_rxd_mux1 >>> | NA | gpio0_14 >>> >>> >>> stty settings >>> speed 9600 baud; line = 0; >>> intr = ^C; quit = ^\; erase = ^?; kill = ^U; eof = ^D; eol = <undef>; >>> eol2 = <undef>; swtch = <undef>; start = ^Q; stop = ^S; susp = ^Z; rprnt >>> = ^R; >>> werase = ^W; lnext = ^V; flush = ^O; min = 1; time = 0; >>> >>> Any Ideas? >>> >> -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
