GSM

The GSM part of the Daughter Board is based on the Telit GE864 - Quad - PY module.

Main Features of this module are:

1. Quad-band EGSM 850 / 900 / 1800 / 1900 MHz

2. Output Power

3. Class 4 [2W] @ 850 / 900 MHz

4. Class 1 [1W] @ 1800 / 1900 MHz

5. Control Via AT Commands

6. SIM access profile

7. Supply voltage range: 3.22-4.5V DC

8. TCP/IP stack access via AT commands

Also for ease of use we have incorporated into the design an SMD SIM card slot, with a Sliding mechanism. This works very well with the enclosure we have designed.

The GSM lines are connected to the IR_RX and IR_TX lines of Gumstix Verdex & Pro accordingly.

GPS

As you can see from the picture, there is NO GPS module included with the PCB. There are however connectors for it marked as U170.

You will also notice that there are 2 pins coming out from the GPS connector marked as BT170. Those pins are for the GPS Backup battery. To better specify which pin is which the TOP pin from the picture above is (+) and the Bottom is (-).

Also note that there are 2 additional Pins that come out from the GPS connector. The RX and TX lines are not only connected to the BT_TX and BT_RX lines of Gumstix Verdex & Pro but also are directed to the P153 USB connector. Please read about the description of those pins in the "USB - Charging" section of this description.

The GPS Module that these connectors are intended for is the GS405. And is sold seperately for this version of the Gizmo. 

LCD

The LCD for which the Gizmo was created is LTE430WQ-F0C LCD with Touchscreen.

The LCD is connected in a 16bit configuration since there are still some questions about functionality of an 18bit configuration. We have noticed that the Frame buffer has (or had) some glitches with this configuration and the only good comments about it came from QT Apps. So we didn't want to make things difficult neither for our selves nor for others.

Also notice from the picture below that there is an R110 pad for a resistor.

This pad is placed between the LCD_EN and 3.3V nets and is there so that if required you could (by shorting it) have the LCD Turned ON all the time by default (whenever power is enabled to the Board). If left untouched then the LCD_EN is controlled by the PIC16F88 to which we shall get in the "Power Control" section.

Also note that the BRT(Brightness) pin from the White LED circuit for the LCD back light is connected to the GPIO17_PWM1 pin on Gumstix Verdex & Pro connector. Enabling you to control the brightness from the Gumstix Platform.

Touchscreen/IO/Audio

The touchscreen of the LCD is connected to the UCB1400 Touch Screen pins and is controlled from there.
Note that there are 2 pads that can be configured as illustrated below.

The R130 if shorted, becomes connected to the A0 pin of UCB1400 and Battery measurements can be made from it. The PLine are the Audio Output lines from the UCB1400. Note that these are Bare outputs with No amplification what so ever.

USB - Charging

There are 2 ways to charge a battery connected to the Gizmo

1. By USB or 5V < 300 mAh Power supply connected to the Power Socket

2. By A direct Battery connection through the Power Socket and an External Li-Po Charger.

You can select one of these modes by Shorting R148 or R149 accordingly. For example in the illustration below, the charging is set to "USB or Power Supply".

We ship this Gizmo with this as the default setting.

The Charging IC that is used here is MAX1555 and is marked as U149 on the PCB. Also when the charging process has started, an LED (above the Power Plug) is turned ON and stays that way until the charging process has finished.

The USB connection is established with the FF_RX and FF_TX pins of the Gumstix platform and are connected to the CP2102 (USB<->UART Bridge). This USB connection is made through the P152 USB Connector (The One on Top)

The Second USB connector (P153) is used for reading the GPS_RX/TX and GSM_RX & TX_Trace signals for debugging or external implementation.

If watching the Connector as it is on the picture above then the pins are:

1. GPS_RX

2. GPS_TX

3. GSM_TRACE_RX

4. GSM_TRACE_TX

5. GND

MMC - Camera

As you can see from the above illustration, the 24pin Flex Connector for the 120pin (or 80pin) Break Out Gizmo is marked as J200 and the Camera Connector is marked as J201.

In order to be able to use the MMC Slot and the Quick Capture signals on Gumstix Verdex & Pro you MUST connect the 24pin Connector with the 120pin (or 80pin) Break Out Gizmo (which should be attached to the 80pin - 120pin header on Gumstix Verdex & Pro) which is NOT included with the Daughter Board 1.0

Power Control

The Power is controlled by 3 Things

1. Power Button (S141)

2. PIC16F88 (U140)

3. Digital Switch LTC1477 (U144)

This is how it works: The PIC16F88 is in Sleep mode when the device is "OFF". When the B0 Interrupt (Power Switch) is toggled then PIC16F88 is woken up and set's the EN (enable) pin on the LTC1477 "HIGH" and also Powering an Internal LED(Green) inside the Power Switch. We made it like this so that we (and everyone else) could play with the Power On Off features and also have some room for experimentation. Also a nice little feature we made is that when the Gizmo Power is enabled (the power switch is Toggled once) Everything Turns On (including GSM, GPS, Gumstix e.c.t) but when you Toggle it After everything is ON then the LCD Turns OFF, If you toggle it once more then the LCD Turns back ON. If the power Switch is pressed for 4 Seconds then the entire system turns back OFF.

Compass

The HMC6352 Compass is NOT included in the 1.0 Version. However, the pads for soldering one are.

Voltage Regulators

There are 3 voltage regulators on the PCB and they are marked on the below illustration

1. LTC3441 - 3.3v For the GPS, Peripherals and the other 2 Regulators

2. MCP1700 1.8v for the Camera

3. MCP1700 2.5v for the Camera

Gumstix Verdex & Pro, GE864 & LCD Back light get their power directly from LTC1477 (Digital Switch).