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HT98R068 Two-way Radio MCU

Automatic Gain Control -- AGC

The audio input magnitude to microphones usually varies influencing the quality of the

audio output. This problem is usually resolved by the addition of an AGC circuit, however

this incurs a costs increase and requires circuit and component space. However this

device includes a fully internal AGC function which when accompanied with its internal

microphone amplifier (with a fixed gain of 5) and digital control, can fully implement an

automatic gain control mechanism. The range from 16mV~135mv (rms) which is selected

using the control bits I/O CMD-2Ch[0].

Audio Control - 2Ch Address

Bit

Name EN_Scram EN_Comp EN_Emp EN_NBW EN_WBW EN_HPF300 EN_VOX EN_AGC

AGC Selection Register

AGC Enable Flow:

Flow description:

<82C01>

：

Setup data

：

01h. 2Ch[0] = 1 enables the AGC function.

AGC application circuit (Gain value = 5 ):

Parameter Setting

The Audio processor frequency generation, threshold detection, variation values, drop

time and limiting values can be modified according to actual requirements and generate

the required setting parameters using the application program in the appendix:



Use the program HT98R068_AppProg_Vxx.exe to generate the required parameters.



For details, see the HT98R068_AppProgNote_Vxx.pdf.

Содержание HT98R068

Страница 1: ...DTMF encoder decoder scramble descramble VOX etc transmitted to the other port through a radio frequency carrier Operating Principles Sub tone processor CTCSS encode decode DCS encode decode In band tone processor DTMF encoder decode Selective call tone EEA standard In band tone user define Other signals DCS turn off tone Advanced audio frequency processor Scrambling Companding Emphasis De emphasi...

Страница 2: ...er PGA and multiplexer that provide selectable audio and modulation signal input such as MICO AUX BEEP1 and DEMI Output unit MOD SMOD The signal output port includes MODO for the baseband signal output and SMODO for the sub tone signal output Output unit Audio The audio output port with selectable DAC1 BEEP0 multiplexed outputs MCU unit The MCU control unit is used to control the user program code...

Страница 3: ...R R The R2 value can be altered according to actual application requirements If the internal AGC function is to be used then the gain needs to have a value of five ex R1 1K R2 5K before using DEMOD is the baseband signal input port after RF demodulation AUX This external audio input supports external audio applications MOD SMOD AUDO Baseband sub tone audio output port The MOD output can generate b...

Страница 4: ...ntrol register 0 CTRL0 Bit No 7 6 5 4 3 2 1 0 CTRL0 PCFG PFDCS PFDC LXTLP CLKMOD POR 0 0 0 0 0 0 0 1 The CTRL0 0 bit selects the MCU speed mode If CTRL0 0 1 the MCU operates in the low speed mode 32 768kHz If CTRL0 0 0 the MCU operates in the PLL mode When using the PLL mode it is important to note that when the PLL is enabled the PLL output and audio processor divider ratio must be first selected...

Страница 5: ...e next step is to enable the audio processor by setting the CTRL2 4 bit which is the audio processor reset signal control bit Use a 1 0 1 sequence which drives POR 0 Also do not set CTRL2 4 1 when configuring the PLL After a reset it is necessary to wait for 100ms 300ms Fsys_Audo 16MHz note before sending instructions This waiting period is for the audio processor internal initialisation including...

Страница 6: ...eset sequence is 1 0 1 with two non operational instructions in between Delay100ms 300ms This is the audio processor initial time Any SPI data transmitted during this period may be overwritten by the audio processor and become invalid Audio Processor Turn on Timing Note Fsys_Audo Audio processor fSYS Audio Processor Turn on Time 6 ...

Страница 7: ...bits of data The group contains both I O and CLI The I O command is used in some application areas such as for circuit control sharing data etc marked as I O CMD NNh in this document The CLI control layer interface command can access the audio processor related parameters such as the threshold parameters modulation advanced application control and so on Its usage is different from the I O group an...

Страница 8: ...n a Don t Care condition during a read command execution A7 A0 is the register addresses D7 D0 is the access data Write I O CMD Master Write SPI 19 16 SPI 15 8 SPI 7 0 4 b1000 Address A7 A0 Data D7 D0 Audio processor reply SPI 19 16 SPI 15 8 SPI 7 0 x No signal x No signal x No signal Read I O CMD Master Write SPI 19 16 SPI 15 8 SPI 7 0 4 b1001 Address A7 A0 x Don t care Audio processor reply SPI ...

Страница 9: ...ssor will continue to receive successive data When the data is written the audio processor will reply with a signal 14000 which means that the data is correctly written otherwise it means no data written Write CLI CMD Master Write CLI_CMD Major Minor Multi Length 4 b0001 4 b0100 4 b0000 4 b1000 4 b0010 4 b0001 Address 15 0 4 b0001 Data 15 0 Audio processor reply CLI_CMD Major Minor Multi Length 4 ...

Страница 10: ...1FFFF Setup data FFFFh Write data to the register A data response of 14000 means that it is correctly written otherwise it means that no data has been correctly written Read 04CBh Flow Flow description 14181 The CLI read ID code To execute a read operation with the CLI command it is necessary to execute this command first No data response will be provided 104CB Select the 04CB register Setup the r...

Страница 11: ...sed for other functions at this time SPICK MOSI MISO SPISS SPIRQ SPICR 7 1 SPICR 3 SPICR 2 SPICR 1 SPICR 4 SPICR 0 SPICR 7 0 PC6 PC4 PA5 PC7 PC5 SPI Control Signal Table Points to note when using external control When required to reduce the PLL frequency or entering the sleep mode When the SPI is returned to the internal MCU control Usable pins decrease For the above problems 1 and 2 it is recomme...

Страница 12: ...h to the correct input or output source and disable any unnecessary circuits so as to save power and eliminate interference among signals This part is part is in the I O command making signal control easier The following describes the three mode setups see SLOW Mode in VOX IDLE Mode When the audio processor is not processing data entering this mode can save power however the quantity depends on th...

Страница 13: ...ding to the input data trigger such as pressing PTT audio signal VOX etc The mode switches input source selection circuit disabling etc will be generally executed in this mode As for the audio buffer input source it is recommended to switch to bias to reduce noise or turn off the buffer I O CMD 1Eh 3 or even choose both During Tx Rx switching it is recommended to execute a circuit ON OFF path sele...

Страница 14: ...ource to the DEMOD path and then enabling the audio processor for management In this way power can be saved and in the meantime prevented from erroneous signal judgments The mode switches path select circuit ON OFF and the SPI command settings are as follows Ex RX mode Input DEMOD Output AUDO sources DAC1 No sub tones Rx mode Setup Flow Flow description RSSI OK Confirm if the RF signal is OK 81E8B...

Страница 15: ...0h 02h IRQ Polling Comparison Table Sub tone Function For open systems such as walkie talkies under conditions of limited frequency channels a sub tone method can be used to increase the same frequency channel numbers and to receive the required signals Users at the receiving port should select the correct sub tone type and channel so as to decode the data properly and reduce unnecessary signals T...

Страница 16: ... 5 10h 114 8 21h 210 7 32h 229 1 11h 118 8 22h 218 1 33h 254 1 CTCSS Frequency vs Tone Numbers Table Ex TX mode Input MIC Output MOD SMOD Sub tone CTCSS CTCSS tone 01h CTCSS Tx mode Setup Flow Flow description 82B01 Setup the sub tone channel by selecting the first group of the CTCSS channel 81E37 Enable the DAC1 DAC2 AMP1 AMP2 MIC and PGA circuits DAC1 AMP1 on enable the MOD output DAC2 AMP2 on e...

Страница 17: ...educe noise 81162 Enter the Rx mode Select the Rx mode and enable the Sub tone CTCSS function Is CTCSS event Wait to confirm that this signal has the CTCSS sub tone of the same channel 81E8B Enable the DAC1 Buffer and PGA circuits DAC1 on and enable the DAC1 output AUDO output buffer on and enable the audio output circuit PGA on and enable the PGA input source 81B25 Select the PGA and Audio input ...

Страница 18: ...65 04h 031 20h 226 3Ch 466 84h 031 A0h 226 BCh 466 05h 032 21h 243 3Dh 503 85h 032 A1h 243 BDh 503 06h 043 22h 244 3Eh 506 86h 043 A2h 244 BEh 506 07h 047 23h 245 3Fh 516 87h 047 A3h 245 BFh 516 08h 051 24h 251 40h 532 88h 051 A4h 251 C0h 532 09h 054 25h 261 41h 546 89h 054 A5h 261 C1h 546 0Ah 065 26h 263 42h 565 8Ah 065 A6h 263 C2h 565 0Bh 071 27h 265 43h 606 8Bh 071 A7h 265 C3h 606 0Ch 072 28h 2...

Страница 19: ... first DCS channel group 81E37 Enable the DAC1 DAC2 AMP1 AMP2 MIC PGA circuits DAC1 AMP1 on enable the MOD output DAC2 AMP2 on enable the SMOD output MIC on enable the microphone circuit PGA on enable the PGA input source 81B10 Select the PGA and audio input source paths Select the PGA input source to be MIC with the audio out to be DAC common mode bias to reduce noise 81142 Enter the Tx mode Sele...

Страница 20: ...ignal DCS sub tone AUDO sources DAC1 DAC2 off MIC off DCS tone 01h all are implemented using interrupts IRQs in this example and use 23h bits for the event status this step can be omitted in practice yet share the same program code with polling When a DCS event interrupt is received add an additional command to read the I O CMD 23h for event status judgment DCS Rx mode Setup Flow 1 RF Signal Detec...

Страница 21: ...interrupt is the DCS sub tone signal of the same channel 92300 Check again the event status which can be shared with the 23h status management program Flow description 3 Is DCS event Wait to check whether this signal contains the DCS sub tone of the same channel 81E8B Enable the DAC1 Buffer PGA circuits DAC1 on enable the DAC1 output AUDO output buffer on enable the audio output circuit PGA on ena...

Страница 22: ...come meaningless and impossible to use Likewise when in the Rx mode after the descrambler is applied the scrambled signals will be returned back to their original signals This function is controlled by the I O CMD 2Ch 7 bit by using the following setup Scrambler Enable Flow Flow description 82C80 Setup data 80h 2Ch 7 1 enables the Scrambler Audio Compandor Compressor Expander Function Setting Comp...

Страница 23: ...o so emphasis will be used to improve this unbalanced situation In the Tx or Rx mode the control bit I O CMD 2Ch 5 is setup as follows Emphasis Enabe Flow Flow description 82C20 Setup data 20h 2Ch 5 1 enables the Emphasis Audio Low Pass Filter High Pass Filter Function Setting In a communication system signal interference and noise from adjacent channels will corrupt the data to be transmitted rec...

Страница 24: ...level select 256 levels Default 00h VR3 Mixer modulation option setting When VR3 0 it means no MIX function 256 levels Default 00h VR4 The MOD pin in band output modulation select 1024 levels Default 3FFh VR5 The SMOD pin sub tone output modulation select 1024 levels Default 3FFh The MOD output depends on the VR1 setting if a tone generator is used VR4 and the system operating voltage The SMOD out...

Страница 25: ...essor writes an acknowledge reply Voice Control Function VOX The VOX function is often used in some special applications From the VOX high level threshold CLI CMD 04CD and low level threshold CLI CMD 04CE which are related to the mic voice volume the input source can be determined whether it is above the threshold I O CMD 29 1 0 02h or below the threshold I O CMD 29 1 0 01h The control bit is I O ...

Страница 26: ...ssor operating frequency 16MHz 4MHz and disable any unused circuits output related components to meet the minimum power consumption 16mA 10mA 3 3v When the signal is acknowledged enter the Tx mode to continue with signal transmission The control flow is shown below VOX Enable Flow 1 VOX and Slow Mode Setting 26 ...

Страница 27: ...L2 7 6 b 00 CTRL2 5 b 1 Set the audio processor to the lowest frequency 4MHz 82C02 Setup data 02h 2Ch 1 1 enables the VOX function Flow description 2 Is VOX event Confirm if it is a VOX event 92900 The VOX high low threshold status Read the VOX threshold status 29h 1 0 b 10 above the high threshold a VOX event 29h 1 0 b 01 below the low threshold end a VOX event 81120 Go back to the slow mode and ...

Страница 28: ... from 16mV 135mv rms which is selected using the control bits I O CMD 2Ch 0 Audio Control 2Ch Address Bit 7 6 5 4 3 2 1 0 Name EN_Scram EN_Comp EN_Emp EN_NBW EN_WBW EN_HPF300 EN_VOX EN_AGC AGC Selection Register AGC Enable Flow Flow description 82C01 Setup data 01h 2Ch 0 1 enables the AGC function AGC application circuit Gain value 5 Parameter Setting The Audio processor frequency generation thres...

Страница 29: ...6 45 VSS VSS 46 45 VSS 37 PA2 44 43 PA3 38 39 PC0 44 43 PC1 40 35 PA0 42 41 PA1 36 41 PC2 42 41 PC3 42 33 PB6 40 39 PB7 34 43 PD4 40 39 PD5 44 NC 38 37 NC 45 PD6 38 37 PD7 46 NC 36 35 NC NC 36 35 NC NC 34 33 NC NC 34 33 PA7 RESB 50 NC 32 31 NC 51 PA6 32 31 PA5 52 NC 30 29 NC 53 PA4 30 29 PC4 54 NC 28 27 NC 55 PC5 28 27 PC6 56 NC 26 25 VDD 27 28 29 57 PC7 26 25 PD0 58 24 XOUT 24 23 VSS 25 26 59 PD1...

Страница 30: ...6 35 NC NC 36 35 NC NC 34 33 NC NC 34 33 PA7 RESB 36 NC 32 31 NC 37 PA6 32 31 PA5 38 NC 30 29 NC 39 PA4 30 29 PC4 40 NC 28 27 NC 41 PC5 28 27 PC6 42 NC 26 25 VDD 25 43 PC7 26 25 PD0 44 23 XOUT 24 23 VSS 24 45 PD1 24 23 NC 21 PLLC 22 21 XIN 22 NC 22 21 VSS 46 19 PB4 20 19 PB5 20 NC 20 19 NC 17 PD2 18 17 PD3 18 NC 18 17 NC 15 PB2 16 15 PB3 16 47 MIC_O 16 15 MIC_I 48 13 PB0 14 13 PB1 14 1 DEMOD 14 13...

Страница 32: ...ˇ ˇ ˇ 16M ˇ ˇ 12M ˇ ˇ ˇ 12M ˇ ˇ ˇ 12M None DTMF Audio Band tone ˇ ˇ ˇ ˇ 16M ˇ ˇ 12M ˇ ˇ ˇ 12M ˇ ˇ ˇ 16M ˇ ˇ ˇ ˇ 16M ˇ ˇ ˇ 12M ˇ ˇ ˇ ˇ 12M ˇ ˇ ˇ ˇ 16M None ˇ ˇ ˇ ˇ ˇ 16M ˇ ˇ 16M ˇ ˇ ˇ 16M CTCSS DTMF Audio Band tone ˇ ˇ ˇ 16M ˇ ˇ 12M ˇ ˇ ˇ 12M ˇ ˇ ˇ 16M ˇ ˇ ˇ ˇ 16M ˇ ˇ ˇ 12M ˇ ˇ ˇ ˇ 12M ˇ ˇ ˇ ˇ 16M None ˇ ˇ ˇ ˇ ˇ 16M ˇ ˇ 16M ˇ ˇ ˇ 16M DCS DTMF Audio Band tone ˇ ˇ ˇ 16M Tx Functional Combination Capa...

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