1.7.1 Revision A
The first production revision of the LAUNCHXL-F280049C was released in July 2018. This revision can be identified by the "MCU025A" silkscreen labeling on the back side of the EVM between the BoosterPack Connector site 1 towards the top of the board.
Various issues and concerns have been Identified on the EVM as listed below:
Known issues:
- There is contention on the primary side power of the USB Isolation IC, ADUM3160 (U3). As VBUS1 is connected to a 5 V supply (USB_VBUS), the internal regulator of the ADUM3160 will provide 3.3 V internally, with the VDD1 pin being an output. In this revision, USB_VCC, a 3.3 V supply, is connected to VDD1 leading to the contention. Any fluctuation of either 3.3 V supply (USB_VCC and ADUM3160 VDD1) may cause currents to be sourced or drawn from either supply. This is a long term reliability concern for both U3 and U101.
- On the PCB, the J6 and J8 labeling is swapped on the silkscreen. J6 is marked as the inner row (pins 71-80) and J8 is marked as the outer row (pins 51-60). This is incorrect and J6 should be on the outer row with (pins 51-60) and J8 is the inner row (pins 71-80).
- Similar to the above, on the MCU025A_Connectors.SchDoc, J6 and J8 should be swapped. In the schematic symbol J8 should be above Pins 31-40, while J6 should be above pins 11-20.
- Similar to the PCB silkscreen and the schematic, the Quick Start Guide insert has the pin numbers for 51-60 listed as J8 and 71-80 listed as J6. This is incorrect; the pin numbers should be swapped.
Special notes and considerations to be aware of:
- A precision reference (U11) is connected to VREFA+ (pin 9) of the TM4C129x device (U2 - the XDS110 MCU). This is not necessary for the operation of the debug probe. VREFA+ (pin 9) can be safely connected directly to VDDA (pin 8). There are no issues with the current configuration; it is an opportunity for BOM cost/simplification for those seeking to replicate this design on their own.
- The EMU package 8.0.903.4 has a firmware update for the XDS110 Debug probe. This update breaks the cJTAG function of the XDS110. Refer to Section A.1, the FAQs, for more information on how to resolve this issue if encountered.