• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 29 subscribers
  • Views 107 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TM4C129ENCPDT: HSSR Operation Questions - Power Cycle + JTAG

Jacob Butler
Intellectual 1330 points
Part Number: TM4C129ENCPDT
Other Parts Discussed in Thread: UNIFLASH

Hello TM4C Team,

Would you be able to help me with a couple questions about the operation of the "HSSR" Hardware System Service Request?

A customer I support is exploring their options for using factory resets before reprogramming with their custom firmware and we are working through different questions on how to implement this.

1. In terms of implementing the factory reset, the HSSR process described in Section 5.2.6.6 of the datasheet mentions it implements a system reset at the end of the process. Does this system reset accomplish a power cycle internally to restore memory settings to factory presets or does it set a pin to a PMIC like I've seen described elsewhere that accomplishes this power cycle? Or does the HSSR process not need a power cycle at all in order to restore the factory presets. Any insight or advice about best practice would be appreciated here.

2. After the HSSR process has been completed are the JTAG pins reset to the factory presets as well? The datasheet section 4.3.1 shows the state of the pins after a "power-on reset or reset caused by the RST input", but I want to confirm this is the case for the system reset mentioned in the HSSR section.

Thanks in advance for your help!

Best Regards,

Jacob Butler

  • +1
    TI__Guru**** 159445 points

    Hi Jacob,

    Jacob Butler said:
    1. In terms of implementing the factory reset, the HSSR process described in Section 5.2.6.6 of the datasheet mentions it implements a system reset at the end of the process. Does this system reset accomplish a power cycle internally to restore memory settings to factory presets or does it set a pin to a PMIC like I've seen described elsewhere that accomplishes this power cycle? Or does the HSSR process not need a power cycle at all in order to restore the factory presets. Any insight or advice about best practice would be appreciated here.

    At the end of the HSSR process, it implements a system reset  A system reset will reset all the logic (e.g. registers) of the microcontroller to its default state. This is not a POR or power cycle as the voltage is still maintained. It does not send any signal to PMIC. Per datasheet, the HSSR is a form of software reset. Although HSSR is documented in the datasheet, we normally suggest "Unlock" described in 4.3.4.3 as the method to restore the device to its factory setting. Uniflash and CCS both support this method of unlocking. Personally, I have never used HSSR. 

    Jacob Butler said:
    2. After the HSSR process has been completed are the JTAG pins reset to the factory presets as well? The datasheet section 4.3.1 shows the state of the pins after a "power-on reset or reset caused by the RST input", but I want to confirm this is the case for the system reset mentioned in the HSSR section.

    JTAG pins (TCK, TMS, TDI, TDO) can be repurposed for GPIO by software. Various reset sources will restore these pins to their JTAG functionality if they were previously changed to GPIO by software. POR will not just reset these pins but also the JTAG module. Please see table 5-2.