Thank you. I had read the document and still have more detailed questions described above.
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Yes the default state of GPIO45 that is documented in AN76405 is different to the default state observed while I2C Boot.
During I2C Boot the state of GPIO45 is TRISTATE.
Thank you for pointing it out. We will look more into it.
But, once the firmware loads, you can change the state of the GPIO to required using CyU3PGpioSetSimpleConfig(). Can you do this to solve the issue at your end?
Regarding I2C frequency, please refer to Bit5:4 of bImageCTL in section 11.1 of the following doc:
C:\Program Files (x86)\Cypress\EZ-USB FX3 SDK\1.3\doc\firmware\FX3_Programmers_Manual.pdf
(Frequency can't be reduced below 100kHz)
Thank you, although I can change the GPIO state by coding, the default state will last from the time the firmware begin to run to the time of the code that changes of GPIO state. This time is very short, but short circuit exist in this short period.
Is there any table tell me each GPIO's state when FX3 is loading firmware? My experiment tell me during this time, not each GPIO is tristated. Some GPIO is low because it can not be pulled high through pull-up resistor.
Thank you for tell me the way to change I2c frequency.
The table in AN76405 which you are referring is the one which tells about the state of GPIOs during the Bootloader execution (that is while FX3 loads firmware over I2C). But as you have pointed the GPIO45 is not HIGH as expected and is Tristated. So, can you please share your schematic with us so that we can see how a short circuit exists when the pin is tristated?
Also let us know the state of which GPIOs other than GPIO45 that you are looking for?
GPIO45 should be high during I2C data downloading. I find it is low or tristate.
GPIO53 should be high during I2C data downloading. I find it is tristate.
GPIO45 is tested when it does not connected with other elements. I use oscilloscope show low when booting and present a short high pulse after booting. If I use USB booting and do not download image, GPIO45 behaves the same as described in doc.
GPIO53 is connected with a pullup resistor and equivalent pulldown resistor. the oscilloscope show middle voltage during booting and high after booting.