We are facing inconsistent booting issue with the Imx.6 solo custom boards with the processor part number MCIMX6S7CVM08AC silicon version 1.1 and V1.2.
Most of the board out of our 120 production units are creating issue. When we are doing a power ON/OFF cycle some times the system doesn't come up, no serial logs, no display, the current consumption of the device is 97mA.
The custom board has been designed with
- i.MX6 solo (MCIMX6S7CVM08AC)
- PMIC (MMPF0100F0AEP)
- DDR3 (IS43TR16128B -125KBLI , 2 no's of 128M x 16 )
- NAND (1GB , SLC NAND)
and the boot mode resister settings are configured for NAND boot.
Analysis till now,
1. Checked the power sequencing of the processor, all the power rails from PMIC and the internal core voltages of the processor are coming in correct sequence
2. POR_B reset from the PMIC is released only after all the power rails are stable.
3. Measued the 24 Mhz clock and 32 Mhz clock once the system is hung, both are present.
4.I could not reproduce the issue when an oscilloscope probe is connected to the clocks and the reset
5.In the working case, 24Mhz clock is stable and PROB comes 16ms after the clock, 32.768Khz clock comes after the PORB signal is de asserted (most of the times, depending on OFF time).
6.I have given a manual reset once the system is hung, then it boots always without any issue.
7. Is this issue related to solo processor errata " ERR007926 : ROM: 32 kHz internal oscillator timing inaccuracy may affect SD/MMC, NAND, and OneNAND boot"
8. We are trying to delay the reset using a 1uF capacitor and try...
Please advice on the same, our production is on hold because of this issue...