That is true, but my problem is that the PIC is looking for 5v signals, and the radio module is only supplying 3.3v signals, so the PIC doesn't properly read the module's output.
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That is true, but my problem is that the PIC is looking for 5v signals, and the radio module is only supplying 3.3v signals, so the PIC doesn't properly read the module's output.
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Depending on the PIC and port pin, a "1" will be any voltage over 1.8 to 2 volts. 3.3 will look like a "1", not a "0". If the PIC is not seeing a "1", something else is wrong. Check the "Tris registers, and if you want to prove the trip point of the PIC yourself, hook a 10K potentiometer to B+ and ground.Next hook the wiper to the pin in question. Write a short program to turn on a LED when the pin goes positive(and off when a zero).Next, measure the voltage.If it's over 3 volts, I'll buy the coffee!
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At least on the PICs I use the hardware SPI pins have Schmidt Trigger buffers and need 0.7*Vcc (3.5V @ 5V) for a logic high.
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Hi,
Some links.
Best regards,
Luciano
Interfacing 3V and 5V applications:
http://www.semiconductors.philips.co...otes/AN240.pdf
Voltage Level Conversion:
http://focus.ti.com/lit/an/swra071/swra071.pdf
* * *
5V to 3.3V and back from 3.3V to 5V
(Works down to 1.5V)
74LVC4245A Octal dual supply translating transceiver; 3-state
http://www.semiconductors.philips.co...LVC4245A_5.pdf
MAX3370/MAX3371 logic level translators
http://pdfserv.maxim-ic.com/en/ds/MAX3370-MAX3371.pdf
More level translators from Maxim:
http://para.maxim-ic.com/cache/en/results/5043.html
* * *
5V to 3.3V
Inputs can be driven from either 3.3 or 5 V devices.
(The 74LVC125A and 74LVC244A will not replace the 74LVC4245A or the MAX3370/MAX337).
74LVC125A:
http://www.semiconductors.philips.co...4LVC125A_4.pdf
74LVC244A:
http://www.semiconductors.philips.co...LVCH244A_4.pdf
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Ok, I successfully got it to receive data using a LVC chip. Now, I have a GPS (CW20 from Navsync - email them for free samples - you just need an antenna) and it has a very vague data sheet. My oscilloscope says it is operating it's serial output at 1.8v. How do i get the PIC to see that? I think a loop back with a max233 might work
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Hi,
Use that:
MAX3370/MAX3371 logic level translators
http://pdfserv.maxim-ic.com/en/ds/MAX3370-MAX3371.pdf
The devices accept VCC from +2.5V to +5.5V
and VL from +1.6V to +5.5V, allowing data transfer
between low-voltage ASICs andhigher voltage devices.
Best regards,
Luciano
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Wow, thanks for your help all
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