Gast
#701783
hab folgendes problem: der mikrocontroller atmega8 versorge ich mit 5V, der sensor braucht aber nur 3V. Also brauche ich einen Pegel converter! habe folgenden gefunden: LM 317T! ist das aber wirklich der passende? zweites problem: der sensor gibt über SPI signale mit 3V aus! erkennt das dann der atmega8 als "high" oder brauche ich da wieder einen pegelwandler? oder was brauche ich da genau (unten ist die FAQ angefügt, dort steht etwas, nur ich verstehe es nicht ganz :-( ) Vielen Dank für Eure Hilfe! Auszug aus FAQ: We just started to work on our first prototype. We plan to interconnect a microcontroller to the pressure sensor. We then realized that our microcontroller sends and receives data signals at 5V, whereas the sensor at 3V. We have discussed this issue between us. There are many techniques available for reducing voltage signals to an acceptable level. You might have had encountered this same problem in the past with other customers. We would therefore like to ask you for help regarding this design issue and if you could share your experience on interconnecting devices. Answer: To convert the signal from 5V to 3V, we suggest to use logic devices of the techology LCX or VHC (see http://www.fairchildsemi.com). For example you might use 74VHC08 or 74LCX04. You supply these parts with 3V and they tolerate 5V inputs without damage. To convert from 3V to 5V (DOUT signal), you need two things: - A buffer supplied at 3V (like the 74VHC08) to give more 'punch' to the DOUT signal (because the MS5534 has not very high output drive capability). - Interface to a TTL compatible device (like 74HCT08) powered at 5V if your microcontroller doesn't accept TTL levels.