some questions about TI Dual SIM IC TXS02326A

Hi, Kenny,

Thanks for your raising your conerns here. below are my feedback for your questions in line with your questions, any further thing, please let me know.

Activation:

What is the role of SIM Interface Control Register for SIMX Activation?

[Junjie] Disable or enable SIMX interface and also choose the regulator output 1.8V or 2.95V.

Will these settings of the registers < Bit7:6(for SIM2) or Bit 3:2 for (for SIM1) > activate the interface of the card (SIMXRST, SIMXCLK, SIMXI/O) as per sequence defined in ISO standards?

[Junjie] I am not sure I know clear about the ISO standards, when you set the < Bit7:6(for SIM2) or Bit 3:2 for (for SIM1) > to 11, it will active the corresponding SIMXRST, SIMXCLK and SIMXIO  interface. For example, if <Bit 3:2 for (for SIM1) > is "11", the SIM1RST will be connectted to SIMRST, the SIM1CLK will be connectted to SIMCLK and SIM1IO will be connectted to the SIMIO. and have the same state high or low. 

Or CPU has to toggle the lines (SIMRST, SIMCLK, SIMI/O) all by itself through GPIO’s?

[Junjie] if you want to get the state you want at SIMXRST , SIMXCLK, SIMXIO, you need to toggle them as what  you wanted. 

As per our understanding, after enabling the bits Bit7:6(for SIM2) or Bit 3:2 for (for SIM1), basically the baseband signals(SIMRST, SIMCLK, SIMI/O) are allowed to be passed directly as corresponding TI-Card interface signals(SIMXRST, SIMXCLK, SIMXI/O). This means, once the said bits are enabled, TI-card interface signals ( SIMXRST, SIMXCLK, SIMXI/O)  are same as corresponding baseband signals (SIMRST, SIMCLK, SIMI/O), apart from any level translation(if occurs any) and without any deliberately inserted internal delay by TI chip. Please confirm whether our understanding is correct?

 [Junjie] yes, you are right.,  TI chip will not add any deliberately internal delay, just the propogation delay which is listed in the Tpd information in datasheet(TPLH and TPHL)

Manual Shutdown:

For SIM X that is not selected (isolated):

Set bits7:6(for SIM2) or bits 3:2 for (for SIM1) to 0x00 in SIM Interface Control Register. These settings of the registers deactivate the interface of the isolated card (SIMXRST, SIMXCLK, SIMXI/O, VSIMX) as per ISO standards. Please confirm if our understanding is correct?

[Junjie] Since I am not clear for the ISO standards, I will say when you set the bits7:6(for SIM2) or bits 3:2 for (for SIM1) to 0x00 in SIM Interface Control Register. the SIMXRST, SIMXCLK and SIMXIO will be in the low state, and disconnect with SIMRST, SIMCLK, SIMIO. no other special actions. if you want to isolate that SIMX, you also need to set bits4(for SIM2) or bits 0for (for SIM1) to 0x00 in SIM Interface Control Register to make the regulator off.

For SIMX that is selected:

What is the role of SIM Interface Control Register for manually shutting down the SIMX that is selected?

1. Do we need to deactivate the baseband signals      (SIMRST, SIMCLK, SIMI/O, VDDI/O) as per ISO standards which in turn will      deactivate the interface of the currently selected card (SIMXRST, SIMXCLK,      SIMXI/O, VSIMX).
2.  Is it required to set Bit7:6(for SIM2) or      Bit 3:2 for (for SIM1) to 0x00 in SIM Interface Control      Register also? If yes, before or after step 1?

[Junjie] Like what I said above, if you only deactivate the baseband signals, the output SIMX interface will be in a unknown state and may cause some problems, if it does need, plesae deactivate the SIMX interface firslty and then baseband signals, actually you don't need to deactivate the baseband signals.

Automatic shutdown:

There is this SDN Status(Bit 0) of Status Register(04h).

1. The shutdown procedure will be initiated or      started when this bit changes from 0 to 1.

      [Junjie] there is a Device contorl register(0E), you can set the BIT 6 to set the active high or active low. and also set BIT7 will set whether the automatic power down sequence will be triggered by SDN signal.

     2. And once the shutdown procedure is completed this      bit changes from 1 to 0.

     [Junjie] since it is the SDN state, it reflect the input of the SDN. I don't think it will change from 1 to 0.

We are interested mainly here as how we would be knowing the shutdown procedure is completed and this can be achieved through the SDN status bit as referred in point 2.

Please let us know if this method is correct?

[Junjie] I don't think it is suitable, based on the datasheet, and shutdown sequence, after SIM2 is pull out, the SIM2 interface will go into power down with pull down activated. which means the Bit7:6(for SIM2) will be "00" at 04 and 08 register and also at the same time the Bit 4(for SIM2) at 08 register will be "0", this is the indication of shutdown sequence is finished.

BR
Junjie