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TM4C1294KCPDT: Data of external SDRAM is corrupt using EPI

Hiroyasu Tazawa1
Guru 12350 points
Part Number: TM4C1294KCPDT

Hi, Everyone

I have a question about EPI of TM4C129x.

My customer connected between TM4C129x and SDRAM.
but Data is corrupted randomly when over 75℃.
It is no probrem when under 75℃. and We use temp semsor on TM4C129x.

We saw this corruption on Memory Browser of CCS.
Memory range of corruption are 0x68003800～ and 0x68020000～.

We saw this issue when System clock is 120MHz and 60MHz.

I already see errata and data sheet.
but I have no idea for this resolve.

Do you have same situation ?

and Do you have any idea ?

Best Regards
Hiroyasu

  • 0
    Guru 117855 points

    Hiroyasu said:
    Do you have any idea ?

    While (far) from "vendor/factory status" - I may qualify to respond under the headings of: "Everyone & Idea holder."

    Your post notes that the (only) temperature measurement occurs via the MCU's designated internal junction.     Three comments thus arrive - immediately:

    • Is 75°C w/in that MCU's (operating) temperature specification?
    • Is that "MCU reported measurement" - alone - sufficiently accurate for a (real) diagnosis?
    • Is the SDRAM spec'ed to operate at/around that temperature?

    Unstated is "how" the MCU has risen to that temperature - such description would be most helpful.      In addition - the deployment of a "second, MCU independent" temperature sensor - is greatly needed.

    From experience - it must be that the "ambient" temperature - at/around the MCU - has risen substantially beyond, "normal, room ambient" - kindly confirm & note the, "measured temperature" (again obtained  via separate, Non-MCU means) for further diagnosis.

    Should the "surrounding ambient" be far less than the 75°C (reported by the MCU) it would appear that the MCU is being "tasked too hard" and/or the power to the MCU is improper.   ("tasked too hard" implies that the MCU is providing output current beyond the device's (MCU's) specified capability.)     Such generates extra heat - and is almost guaranteed to prove damaging to the MCU.

    If the MCU is "spec'ed to operate @ 75°C" and no other MCU specs are being violated - it may be possible to "operate at that temperature" by adding a special heat-sink and efficient, "Thermal Insulating Material" - which both "bonds" the heat-sink to the MCU while providing effective heat transfer into the heat-sink...

  • 0
    TI__Guru 72500 points
    I suggest that they carefully verify the timings between the TM4C1294KCPDT and the DRAM. Also note that they must use 8mA drive when interfacing to the SDRAM. The SDRAM may appear to work even though the timings are out of spec at lower temperature, but fail at higher temperatures.