AirPrime MC7304 N.C. pins

IoT Modules MC/EM Series
1

I have a question on the exact definition of “not connect” pins on the AirPrime module. Datasheet (Product Technical Specification & Customer Design Guidelines AirPrime MC7304, 4114634, Rev 2) on page 26 contains a note: The host should leave all ‘NC’ (‘no connect) pins unconnected. Unfortunately, it is generally very difficult, because different modem manufacturers have differences in modem pinout (especially in case of SIM detection input etc.). Ideally we need a list of pins with the definition of what should be left unconnected, and what are unconnected to the module (=can be connected to some signal).

At this moment, for us the critical pins are:
16 UIM_VPP (conflict with SIM detection of other modems)
17 Reserved/UIM_C8 (conflict with SIM detection of other modems)
19 Reserved/UIM_C4 (conflict with SIM detection of other modems)
22 PERST# (conflict with RESET of other modems)

Thanks for the answer

Jiri

2

Hi,

The pins which should be left unconnected are already mentioned in the PTS. Also, from my understanding, you are trying to interface our module with some other modem? is it? The pins what you have listed are the pins of some other modem … right?

What exactly is the conflict you are talking about? Do you want to connect to PIN 16, 17 ,19 and 22 of MC 7304 to some other signals?

Use case?

3

Hi Alex,

I’m preparing our CPU board to connect miniPCIe modem. We have chosen three specific modems for preproduction testing (MC7304 is one of them). Comparing the pinout of these modems I found some conflicts. We need to connect signals to the miniPCIe slot to allow usage of anyone from these three modems. Therefore, we need more information about N. C. pins (because sometime N.C. means do not connect any signal, pin is used for testing, factory programming, etc.").
Conflicts in detail:

pin 16

  • miniPCIe specification defines: UIM_VPP
  • Sierra Wireless PTS defines: N.C.
  • modem of some competitor: use pin as SIM detection
    :exclamation: PROBLEM: SIM detection signal connected to N.C. pin (voltage levels are GND or UIM_PWR via pull-up)
    :question: QUESTION: can we connect the SIM detection signal to pin 16 of MC7304 ???

pin 17

  • miniPCIe specification defines: Reserved/UIM_C8
  • modem of some competitor: use pin as SIM_GND (dedicated GND for improve EMC)
    :exclamation: PROBLEM: SIM_GND connected to N.C. pin (connected to system GND)
    :question: QUESTION: can we connect the SIM_GND (=GND) to pin 17 of MC7304 ???

pin 19

  • miniPCIe specification defines: Reserved/UIM_C4
  • modem of some competitor: use pin as SIM detection
    :exclamation: PROBLEM: SIM detection signal connected to N.C. pin (voltage levels are GND or UIM_PWR via pull-up)
    :question: QUESTION: can we connect the SIM detection signal to pin 19 of MC7304 ???

pin 22

  • miniPCIe specification defines: PERST#
  • modem of some competitor: use pin as RESET
    :exclamation: PROBLEM: System RESET signal connected to N.C. pin (voltage levels are GND or 3V3)
    :question: QUESTION: can we connect the system RESET signal to pin 22 of MC7304 ???

I hope it is clear now :wink: I just need to connect some signals (used by modems of competitors) to miniPCIe connector, but without risk of MC7304 malfunction.

4

Hi,

There are risk of MC card malfunction. If it is mentioned as NC pin, then we should not connect it.

Thanks

5

Can you be more concrete???

This means that the modem is not compatible with MiniPCIe standard…

6

Hi,

We deviate from the spec in order to add additional functionality. Compatibility with PC mother boards varies depending on how the vendor wired up their interface.