AT COMMAND SET HILO/HILONC MODULES - Libelium

page 225/33912. AUDIO COMMANDS12.1. Preliminary commentsThe current “preliminary comments” section deals with AT commands: VIP, VGR, VGT, KVGR,KVGT, KECHO, KNOISE, KST, KPC and KSRAP.12.1.1. General BehaviorThe commands cited above and presented here after can be used to tune audio parameters such asgain (up and down), volume, side tone, modes (handset, handsfree, …) and to activate some audiofeatures such as noise reduction, echo cancellation and peak compressor. The following sections willindicate how to use the commands and with which parameters.To explain briefly the global behaviour, it is important to note that the audio parameters are stored inFLASH memory and loaded into RAM at each power up. The parameters are divided into organs,each configuration (handset, handsfree) are in fact a couple of one RX organ and one TX organ. Thecommand AT+VIP will allow to choose a configuration, so a couple of organs.At the beginning of a call, selected organs are sent to the DSP.The modifications done by the commands described after will modify audio parameter values inRAM. If the user does not save the values, they will be lost at the next power up. Nevertheless, acommand allows the user to save values in FLASH and also allows to restore initial parameter values(the ones set prior to make any change on audio parameters).12.1.2. WarningThe AT+VIP commands has 2 purposes. First, it selects the current context (handset, handsfree) foruser modifications; call it “parameter change context”. Secondly, it pre-selects the context that will besent to the DSP for a communication; call it “pre-selected communication context”.A problem is that these 2 contexts have not the same “time to live”.The “parameter change context” lasts between 2 AT+VIP commands.The “pre-selected communication context” lasts from the AT+VIP command to the end of a call. The“pre-selected communication context” value will be reset after a call but the “parameter changecontext” will remain the same after the call release.Here is an example:AT+VIP=1AT+KVGR=”10”ATDxxxxxxx;ATHAT+KVGR=”5”ATDxxxxxxx;AT+VIP=0AT+KVGT=”-5”