I just finished designing a board with two UCD9240 parts. I did not thoroughly study the UCD9240 datasheet and falsely assumed that I could simply control unused pins, configured as GPIO, through the PMBus. Unfortunately the board is finished and I'm looking for a workaround.
I have an FPGA that is the I2C master of the bus. I would like the FPGA to be able to write some PMBus commands to the UCD9240 in order to actively drive the DPWM-1B, DPWM-2B, SRE-1B, and SRE-2B pins with an arbitrary state. I understand it is not possible to simply write to a firmware register to change the state of the GPIO. I was wondering if it is theoretically possible to reprogram these GPIO on-the-fly? Suppose I configure one of these pins to drive active-high as long as Rail #X is within it's programmed limits, and then reprogram it to drive active-low instead?
I was planning to try this, but since I don't have much experience with the PMBus, I was hoping an expert could give me some advice before I spend a lot of time designing I2C command sequences.
It is possible to change the configuration of a GPIO pin with a PMBus command but GPIO functionality is a very low level process in the controller and requires that the device be in a non-converting state (no rails converting power) to be processed. I've never tried it but changing the active state of a pin defined as a GPO should force it to change its output assuming it will still function if not set to monitor a particular function. So if you can disable rail operation between chanaging the GPO states than it may work.
All content and materials on this site are provided "as is". TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with regard to these materials, including but not limited to all implied warranties and conditions of merchantability, fitness for a particular purpose, title and non-infringement of any third party intellectual property right. TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with respect to these materials. No license, either express or implied, by estoppel or otherwise, is granted by TI. Use of the information on this site may require a license from a third party, or a license from TI.
TI is a global semiconductor design and manufacturing company. Innovate with 100,000+ analog ICs andembedded processors, along with software, tools and the industry’s largest sales/support staff.