Q24 Series - Hardware and datasheet doubts


I am new in the forum.
I am working with Q24 and Q26 modules and I have some doubts about the Q24 series, described below.

I have around 2000~2500 pcs of Q24 modules that was used in an old project of a friend.
I will re-use them in a little new design.

The datashet revision I have is the latest one: AirPrime Q24 Series Product Technical Specification - Rev7.1 - February 23, 2012

  1. MAIN QUESTION:I am going to interface with a GPS module through UART2 (auxiliary UART) just by using the pins TXD2 and RXD2. The GPS module doesn’t has RTS and CTS pins. What should I do with pins RTS2 and CTS2 of Q24 module? Do I need to short-circuit them?

Another doubt about UART2: Can I interface with the GPS module through UART2 just by using TXD2 and RXD2 pins, and use the CTS2 and RTS2 from UART2 as GPIO purposes (GPIO0 and GPIO5) at the same time? This way, I would have two additional I/O’s in my PCB layout, while mantaining communication with the GPS through pins TXD2 and RXD2. That would be great!

  1. About the nRST pin, the datashet shows (on page 52) that it has an internal pull-up resistor to the internal 2,8V power supply. What is the typical value of this resistor? I didn’t found the value of this resistor in the datasheet. Is it 100K ohms?

  2. I will use only the SimCard socket present at the top of the module, and not use an additional SimCard socket in the PCB layout. This way, I need to connect the SIM_PRES pin to the 2,8V output of Q24, right? Or it is better to use a pull-up resistor with low value (1K ohm, for example) between SIM_PRES and 2,8V?

  3. I won’t use the Q24’s internal RTC. Therefore I will leave the VCC_RTC pin floating in the PCB? Any problem about that?

  4. Page 22 of datasheet shows that the maximum supply voltage is 4.5VDC (at VBATT and VDD pins). In this design I will supply the Q24 with a precision/high current capability 4,2V (or maybe 4,1V) power supply. Any problem about that?
    OBS: At the VCC pin (2,8V output of Q24, pin 11) I will draw 10mA, in the worst case (maximum consumption at this output will be 10mA).

  5. I will use the ~INTR pin as a digital INPUT (using interrupts). I have never used this pin before. Is there any issue related to this pin?

  6. I won’t use a keyboard. Is it possible to use COL0 to COL4 and ROW0 to ROW4 pins as digital INPUTS?

No help?


Unfortunately, Q24 series is not supported anymore. Please contact Sierra Wireless distributor for the latest modems that fits your requirement.