Specifications

AC65/AC75 Hardware Interface Description

3.3 Power-Up / Power-Down Scenarios

AC65_AC75_HD_v01.002 Page 37 of 117 2006-10-30

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3.3.3.3 Turn on/off AC65/AC75 Applications with Integrated USB

In a Windows environment, the USB COM port emulation causes the USB port of AC65/AC75 to appear as a

virtual COM port (VCOM port). The VCOM port emulation is only present when Windows can communicate with

the module, and is lost when the module shuts down. Therefore, the host application or Terminal program must

be disconnected from the USB VCOM port each time the module is restarted.

Restart after shutdown with AT^SMSO:

After entering the power-down command AT^SMSO on one of the interfaces (ASC0, ASC1, USB) the host appli-

cation or Terminal program used on the USB VCOM port must be closed before the module is restarted by acti-

vating the IGT line.

Software reset with AT+CFUN=x,1:

Likewise, when using the reset command AT+CFUN=x,1 on one of the interfaces (ASC0, ASC1, USB) ensure

that the host application or Terminal program on the USB VCOM port be closed down before the module restarts.

Note that if AT+CFUN=x,1 is entered on the USB interface the application or Terminal program on the USB

VCOM port must be closed immediately after the response OK is returned.

3.3.4 Automatic Shutdown

Automatic shutdown takes effect if:

• the AC65/AC75 board is exceeding the critical limits of overtemperature or undertemperature

• the battery is exceeding the critical limits of overtemperature or undertemperature

• undervoltage or overvoltage is detected

See Charge-only mode described in Section 3.5.7 for exceptions.

The automatic shutdown procedure is equivalent to the Power-down initiated with the AT^SMSO command, i.e.

AC65/AC75 logs off from the network and the software enters a secure state avoiding loss of data.

Alert messages transmitted before the device switches off are implemented as Unsolicited Result Codes

(URCs). The presentation of these URCs can be enabled or disabled with the two AT commands AT^SBC and

AT^SCTM. The URC presentation mode varies with the condition, please see Section 3.3.4.1 to Section 3.3.4.5

for details. For further instructions on AT commands refer to [1].

3.3.4.1 Thermal Shutdown

The board temperature is constantly monitored by an internal NTC resistor located on the PCB. The NTC that

detects the battery temperature must be part of the battery pack circuit as described in Section 3.5.3 The values

detected by either NTC resistor are measured directly on the board or the battery and therefore, are not fully

identical with the ambient temperature.

Each time the board or battery temperature goes out of range or back to normal, AC65/AC75 instantly displays

an alert (if enabled).

• URCs indicating the level "1" or "-1" allow the user to take appropriate precautions, such as protecting the

module from exposure to extreme conditions. The presentation of the URCs depends on the settings selected

with the AT^SCTM write command:

AT^SCTM=1: Presentation of URCs is always enabled.

AT^SCTM=0 (default): Presentation of URCs is enabled during the 2 minute guard period after start-up of

AC65/AC75. After expiry of the 2 minute guard period, the presentation will be disabled, i.e. no URCs with

alert levels "1" or ''-1" will be generated.

• URCs indicating the level "2" or "-2" are instantly followed by an orderly shutdown, except in cases described

in Section 3.3.4.2. The presentation of these URCs is always enabled, i.e. they will be output even though the

factory setting AT^SCTM=0 was never changed.