On Tue, 10 Mar 2015 22:07:38 -0700 (PDT), you wrote: >If your data rate is very high, level shifter TXB0104 or TXB0108 may not be >a good option since the level transition is not very smooth. For faster >data rates use open collector buffer(7407 ic) circuit give at >http://elinux.org/RPi_GPIO_Interface_Circuits
If the level transition is not very good, (noisy or irregular perhaps), then using an input with hysteresis is a good idea. An open collector buffer has a rise time at the output determined by the pullup resistance and the capacitance at that pin (from anything). It is generally very slow since there is no low impedance (say 20 ohms of an active transistor) pulling it up. You can get either a 74 series level translator as a DIP package, or you can get surface mount. if you want surface mount and need only one line, then try the 1G series logic. The chips have two VCC supplies, one can be used for 5 volts, one can be used for 3.3. These chips are bidirectional, so will translate from one level to the other depending on the state of the direction line. They are designed to work in less than optimum conditions. Harvey > >On Sunday, 24 August 2014 01:00:19 UTC+5:30, Onkar Desai wrote: >> >> >> Hi all, >> >> I am newbie to BBB. I am planning to interface a speed sensor to BBB which >> produces output pulses. >> >> These pulses have, >> >> HIGH level voltage = 4.2 V and LOW level voltage = 0.52 V >> >> Can I interface it directly to BBB ? or should I put a resistor divider ? >> >> Is there any better way out ? >> >> Thank you, >> Onkar >> -- 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 [email protected]. For more options, visit https://groups.google.com/d/optout.
