Hi Team,
My customer using 3.3V external clock source directly connected to X1 pin with TMS320F28069PZP usage, and the XCLKIN used as input GPIO, and reported an that when the XCLKIN input 3KHz(also tried 1Khz-100Khz) Square waveform, the F28069 reported work at abnormal states.
Checked with customer, and configured the software as below: and if XCLKIN input 3Khz(also tried 1kHz-100Khz) square waveform, the F28069 still can work.
EALLOW;
SysCtrlRegs.CLKCTL.bit.XTALOSCOFF = 0; // Turn on XTALOSC
SysCtrlRegs.CLKCTL.bit.XCLKINOFF = 1; // Turn off XCLKIN
SysCtrlRegs.CLKCTL.bit.OSCCLKSRC2SEL = 0; // Switch to external clock
SysCtrlRegs.CLKCTL.bit.OSCCLKSRCSEL = 1; // Switch from INTOSC1 to INTOSC2/ext clk
SysCtrlRegs.CLKCTL.bit.WDCLKSRCSEL = 0; // Clock Watchdog off of INTOSC1 always
SysCtrlRegs.CLKCTL.bit.INTOSC2OFF = 1; // Turn off INTOSC2
SysCtrlRegs.CLKCTL.bit.INTOSC1OFF = 0; // Leave INTOSC1 on
EDIS;
Need you kindly support on below questions:
1.
EDIS;
Reproduced the Step1 operation, no abnormal reported as step1;
Support Need:
As datasheet mentioned, the XCLKIN can connect to 3.3V external clock source, X1&X2 can used as clock source with on-chip crystal oscillator, and X1 voltage is limited in 1.8V level. Currently customer hardware design is out of TI F28069 spec required(X1 as external 3.3V clock source), and plan to modify to correct way, but for the auto shipped out, customer want TI to provide below support to help them to evaluate their next step operation.
1. Share the On-chip crystal oscillator internal schematic or block diagram, as customer connect X1 to 3.3v, which required 1.8V, customer need the schematic or diagram to evaluate the risk;
2. Give comments for the reason why on-chip crystal oscillator is off, but the X1 signal still get through and worked as clock source?
3. other solutions with current hardware?
Best Regards
Benjamin
