User's Manual
Table Of Contents
- 1: Purpose
- 2: Scope
- 3: VAM-CM Overview
- 4: VAM-CM interfaces
- 4.1: Absolute maximum ratings
- 4.2: VAM Control interface description
- 4.2.1: System USB description
- 4.2.2: USIM interface description
- 4.2.3: VAM control UART interface description
- 4.2.4: Analog Audio interface description
- 4.2.5: Digital Audio interface description
- 4.2.6: Power Supply interface description
- 4.2.7: External VRTC Supply Functionality
- 4.2.8: Control and ID interface description
- 4.3: Radio interface description
- 4.4: VAM-CM Power Management Handling
- 4.5: Mechanical interface
- 4.6: Environmental conditions
- 5: Evaluation tools
DRAFT
4: VAM-CM interfaces
Back-up voltage is internally supplied in VAM-CM meaning that if 3v9 Supply is available for VAM-
CM, also internal back-up voltage is present. Powering off the VAM-CM does not shut down internal
back-up voltage supply. Omission of Ext Vrtc supply has influence only in case that 3v9 Supply is cut
off for some reason.
Back-up voltage keeps on the slow clock (32kHz), RTC date information and GPS satellite status
information. When back-up voltage goes down this information is lost and VAM-CM needs to make
cold start which will add about 35 seconds (GPS fix, TTA calculation) to warm start time.
4.2.8:Control and ID interface description
The Control and ID interface is provided to set dedicated operating modes for VAM-CM for different
use cases. These modes can be related for boot-up or control mode. Control and ID interface is
connected via level shifter circuit which allows VAM terminal to determine the signal voltage level
using V_io pin in VAM-CM system connector (
Table 8
). Power on/off control is not connected via level
shifter to enable powering up the VAM-CM when level shifters are not active.
Control and ID interface pins are located in VAM Control interface as described in
Table 9
Pin Signal In/Out Description
#17 Power On/Off In "0,5…1s LOW pulse" Turns modem on or off depending of current
state.
"FLOAT" = Rest state no action
#20 VAM-CM Sleep Out Indicates VAM-CM sleep mode status
"HIGH" – Modem Active
"LOW" – Modem Sleep
#22 VAM-CM Wake-
up
In VAM-CM wake-up control input
"Rising edge" – Modem wake-up
#38 TX Disable In VAM-CM transmitter control input
"LOW" = TX operation of VAM-CM disabled
"HIGH" = normal operation
#39 Modem OK Out Indicates modem status
"LOW" = Modem not ready for operation
"HIGH" = Modem OK
#40 Modem RST In Warm reset for VAM-CM
"LOW" pulse for 1s to reset the VAM-CM
"High" normal operation
#41 TTA Not OK Out Modem synchronization status
"LOW" = Modem is OK for calls
"HIGH" = No TTA available
#42 VAM Boot 1 In Control interface selection.
"LOW" = during power on for USB control
"HIGH" = during power on for UART control
Table 9. Control and ID interface pins
17:GSPS Core Module 2.0 VAM-CM HW Description
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