9 Replies Latest reply on Mar 1, 2019 4:38 AM by jilic_4052711

    CY7C65211 - USB Serial SDK: Long delays between I2C read/writes

    mama_1614126

      I'm using the USB Serial SDK to build a USB-I2C bridge with the CY7C65211 broken off a CY8CKIT-049-42XX. As a first step I'm reading some "who am i" registers, and on the face of it that works fine, so far.

       

      However, on the logic analyzer I see a long delay of 3-8ms between the I2C write and the read. (The two rather randomly chosen test devices, INA219 and MPU6050, require to first set the register pointer with a 1-byte write followed by a 1-byte read.)

      It is clearly the master who is responsible for this, because in the 3-8ms waiting period the clock is low - which I find a bit strange, too.

      Those 3-8ms equate to 125-333Hz, which is quite slow given the capabilities of the device and USB itself.

       

      What is the reason for this delay? Can it be avoided or is there anything to watch out for?

       

      The C program is absolutely straightforward: Open device, write, read, close. The CY7C65211 has the default configuration, just with the switch to I2C.