Dear Everyone,
I am using a SPI protocol where my master ADAS1000(3.3v) should be connected through level shifter 74HC4050N or 74HC125An for adjust voltage level 5v to 3.3 or 3.3v to 5v.
My input master pins of SS,MISO.MOSI,SCK,DRDY works at 3.3v with 2-2.2 micro amp current.
74HC4050N or 74HC125AN datasheet says their per pin input current is 20 mA.
What to do for this connection circuit? Should I need any pull up resister or voltage divider/ current booster
Only 1 resistor is needed. If you can follow this, you can see where I used 74HC4050 (U9) between '1284P and SD card socket for 5V to 3.3V buffering, and 74H125 (U10) on MISO coming back for 3.3V to 5V buffering.
Put a pullup on the SS output from the processor to keep SS to the slave disabled until your sketch kicks in to control the line.
Thank you sir for your kind help!
How about the other other pins from master MISO,MOSI,DRDY? SCK should be connect directly?
In your diagram U9D to U9F pins 10k pull up register has been added.
Do you recommend me the attached diagram that people used before ?
SCK, MOSI, SS from processor should go thru 74HC4050, with a pullup on SS going into the 4050 input, and SS also controlling the OE of the 74HC125 gates.
MISO, DRDY should come back thru 74HC125.
Thus the SD card only sees a valid chip select when the sketch is running, and is not exposed to 5V signal on MISO, DRDY from other devices on the SPI bus.
(SD card does not have a DRDY output, not sure why you bring that up).
Dear Sir,
Thank you for your response.
I get little bit of confusion.
My Master is ADAS10009(3.3v) and slave is Arduino Uno(5v).
They way you are describing what I have mentioned ?
ADASxxx can go thru 5V powered 74AC125 to send to Arduino.
Arduino can go thru 3.3V powered 74HC4050 to send to ADASxxxx.
