VS10xx Debug

Installing and using VSIDE tools for VLSI Solution's devices that contain a VSDSP signal processor.
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VS10xx Debug

Post by Julian » Thu 2010-09-16 19:26

Are the UART pins (TXD and RXD) 5V tollerant? The data sheet simply defines it as a UART and information on your recommended cable does not mention logic levels.

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Re: VS10xx Debug

Post by Panu » Thu 2010-09-16 20:09

No, there are no 5V tolerant I/O pins in VS10xx chips, sorry.

Actually, the datasheet says that RX pin is of type DI and that DI is a "Digital Input, CMOS Input Pad", and at datasheet chapter 4.5, "Digital Characteristics" it says that high level input voltage maximum is IOVDD+0.3 and the footnote says "Must not exceed 3.6 V". All in all, it's a very typical CMOS signal.

The VSIDE USB UART cable provides 3 V signals, which can be connected to VS10xx RX/TX pins.

If you need to connect a 5V signal to RX pin, you could always use a resistor divider to drive the RX signal. For example, from the 5V signal, 2.2 kOhm to VS10xx RX and from VS10xx RX, 2.7 kOhm to GND. That would be nicely compatible with the most common IOVDD selection of 2.7 volts. TX from VS1053 from a 5V uart input would need some checking of the input pad's characteristics... it's difficult to say, because 5V chips are not very common these days. Personally, if I would need to drive a real, classic style 5V chip in a product, I'd use a proper level shifter with separate 5V VDD inputs. But if it's just for personal debugging use, I'd just hack something that would be compatible with the receiver pin. If you tell me exactly what you need to drive, I can of course help you.

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Panu-Kristian Poiksalo, VLSI Solution Oy

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