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Holtek HT98R068 Manual

Two-way radio mcu
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HT98R068 Two-way Radio MCU
D/N：HA0278E
Introduction
The HT98R068, designed by Holtek, is an OTP (One-Time Programmable) MCU
specifically designed for two-way radio communication applications. The internal in-band
tone/sub-tone processor supports functions, such as emphasis/de-emphasis, CTCSS/DCS
encoder/decoder, 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-emphasis
 Digital filter: 12.5k / 25k / HPF(300) Filter
Baseband signal level adjustment function
Voice control (VOX)
MIC AGC
HT98R068 Two-way Radio MCU
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Summary of Contents for Holtek HT98R068

  • Page 1 HT98R068 Two-way Radio MCU D/N：HA0278E Introduction The HT98R068, designed by Holtek, is an OTP (One-Time Programmable) MCU specifically designed for two-way radio communication applications. The internal in-band tone/sub-tone processor supports functions, such as emphasis/de-emphasis, CTCSS/DCS encoder/decoder, DTMF encoder/decoder, scramble/descramble, VOX…etc., transmitted to the other port through a radio frequency carrier.

  • Page 2: Block Diagram

    HT98R068 Two-way Radio MCU Block Diagram Hardware Block Function Description  Audio processor unit: A signal processing unit, responsible for the audio and signal processing.  Input unit: The input source option, including MIC OPA, multiplexer, PGA and multiplexer that provide selectable audio and modulation signal input, such as MICO, AUX, BEEP1 and DEMI.

  • Page 3: Application Circuit

    HT98R068 Two-way Radio MCU Application Circuit The application circuit is divided into three main parts.  Clock/PLL circuit: Y1, R5, C13 and C14 form the PLL external clock source where Y1 is a 32.768KHz crystal to lock the PLL to the setup frequency. R4, C11, C12 are the PLL filter circuits.
  • Page 4 HT98R068 Two-way Radio MCU System Clock Switches Controlled by two registers: CTRL2[7-5,3-0] and CTRL0[0]. The description is as follows: System Control register 2 (CTRL2) Bit # CTRL2 PLLD2 AUPRST PLLEN PLLD1 PLLD0 LXTEN CTRL2[3]:This bit controls the PLL on/off function. The CTRL2[7-6] bits select the PLL output frequency which has four system frequencies to meet different application requirements.
  • Page 5 HT98R068 Two-way Radio MCU PLL Control Flow - for MCU Flow description: <Set … PLL>: Setup the PLL divider and PLL enable. <Delay10ms>: Delay 10ms which is to wait for the PLL to stabilise <CLKMOD=0>: Set the MCU to be in the PLL mode.
  • Page 6 HT98R068 Two-way Radio MCU Audio Processor Reset Flow Flow description: <CTRL2[4]>: This is the audio processor reset bit. The correct reset 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.
  • Page 7 HT98R068 Two-way Radio MCU SPI Command The audio processor uses the SPI interface as the communication interface with two methods of communicating through the internal (SPICR[7]=1) SPI circuit or the external (SPICR[7]=0) pin-shared I/Os. The internal communication can execute the circuit control...
  • Page 8 HT98R068 Two-way Radio MCU SPI Application Example Program The source codes are attached in the HT98R068_AppInc.inc file where the SPI application section contains:  SPI command Macro = SPITX (macro)  SPI Write = Procedure_SPI_Tx (procedure)  SPI Read = Procedure_SPI_Rx (procedure) ...
  • Page 9 HT98R068 Two-way Radio MCU  Read 1Eh Flow Flow description: <91E00>: Read the 1Eh register. A data response will be sent to 1Eh after this command is transmitted. CLI Command This interface protocol is different from the I/O command. For the write mode it must contain three blocks of 20-bits of SPI data and two for the read mode.
  • Page 10 HT98R068 Two-way Radio MCU  Write 04CBh Flow Flow description: <14082>: The CLI write ID code. To execute a write 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 as a write register. No data response will be provided.
  • Page 11 HT98R068 Two-way Radio MCU External Control For different audio processing control requirements, in addition to the internal MCU connections, external SPI control is also supported. However, before using the external control, some relevant initialisation must be executed which includes the PLL, Reset and SPI path.
  • Page 12 HT98R068 Two-way Radio MCU  Use External Control Flow Flow description: <PLL setting …>: Enable and setup the PLL. <Audio processor …>: Reset the audio processor. <Control Signal status>: Check the control signal status and select the SPI path to be external or internal.
  • Page 13 HT98R068 Two-way Radio MCU  Audio processor turn on/off using SPI command flow Flow description: When there is no output and the input signals are waiting to be processed, the audio processor can be disabled. After waiting immediate operating can be restarted without needing to re-initialise.
  • Page 14 HT98R068 Two-way Radio MCU Flow description: <81E97>: Enable the DAC1, AMP1, MIC, PGA circuits. Setup the circuit switch first. DAC1, AMP1 on-enable the MOD output. MIC on–enable the microphone circuit. PGA on–enable the PGA input source. <81B10>: Select the PGA, audio input source locations. Select the PGA input source to be MIC and the audio out to be DAC common-mode bias to reduce noise.
  • Page 15 HT98R068 Two-way Radio MCU Audio Processor IRQ When an audio processing event occurs, the audio processor will use this signal as an interrupt request, during which time the master should send an SPI signal to read the 20-bits of data, transmitting 100h as the first 12 bits of data with the last data corresponding to the I/O CMD-23h, and then identify what kind of the interrupt it is.
  • Page 16 HT98R068 Two-way Radio MCU Tone CTCSS Tone CTCSS Tone CTCSS number freq.(Hz) number freq.(Hz) number freq.(Hz) 225.7 71.9 127.3 12205 74.4 131.8 241.8 136.5 250.3 79.7 141.3 69.3 82.5 146.2 62.5 85.4 151.4 159.8 88.5 156.7 165.5 91.5 162.2 171.3 94.8...
  • Page 17 HT98R068 Two-way Radio MCU Ex: RX mode, Input = DEMOD, Output = AUDO(sources = DAC1), Sub-tone = CTCSS, CTCSS tone=01h CTCSS Rx mode Setup Flow: Flow description: <RSSI OK>: Confirm the RF signal is OK. <81EC3>: Enable the PGA circuit. PGA on and enable the PGA input source.
  • Page 18 HT98R068 Two-way Radio MCU DCS Setup DCS is a data waveform formed by a digital carrier signals using “0” and “1” data. The 23 bit data signal includes the checksum and data codes. It provides a choice of 83x2 (reverse codes included) standard channels and one user-defined channel. A DCS event...
  • Page 19 HT98R068 Two-way Radio MCU Ex: TX mode, Input = MIC, Output = MOD & SMOD, Sub-tone = DCS, DCS tone=01h DCS Tx mode Setup Flow: (1) Tx DCS signal: (2)Transmit an off tone signal at the end of the signal: Flow description (1): <82B01>：Setup the sub-tone channel by selecting the first DCS channel group.
  • Page 20 HT98R068 Two-way Radio MCU * * * After the DCS signal is transmitted * * * Flow description (2): <82B7F>：Select the OFF-tone to produce 134Hz signals. <81101>：Return to the idle mode. Complete the DCS and return to the standby status.
  • Page 21 HT98R068 Two-way Radio MCU (3): Enable and output the Audio_out signal: Flow description (1): <RSSI OK>：Confirm the RF signal is OK. <81EC3>：Enable the PGA circuit. PGA on - enable the PGA input source. <81B30>：Select the PGA and Audio input source paths. Select the PGA input source to be DEMOD and audio out to be DAC common-mode bias to reduce noise.
  • Page 22 HT98R068 Two-way Radio MCU Audio Advanced Function The device provides multiple audio processors, including Scrambler, Compandor, Emphasis, HPF, LPF…etc. for a wide range of applications. The function switches are located at I/O CMD-2Ch[7-2]. As the Audio Processor operating frequencies are different, there are some restrictions in enabling the function groups and for using the Tx/Rx.
  • Page 23 HT98R068 Two-way Radio MCU Compandor Enable Flow: Flow description: <82C40>：Setup data: 40h. 2Ch[6] = 1 enables the Compandor. Audio -- Pre-emphasis \ De-emphasis Function Setting The Emphasis function is used to modulate the high/low frequencies of the power spectrum so as to obtain a more average power spectrum density and a better S/N ratio.
  • Page 24 HT98R068 Two-way Radio MCU Flow description: <82C14>：Setup data: 14h. 2Ch[4] = 1 enables 12.5k LPF. 2Ch[2] = 1 enables 300Hz HPF. In-band Signal Level Adjustment Function The output modulation differs between different system applications. The device provides multi-level modulating settings for different paths and also provides a mixer. The...
  • Page 25 HT98R068 Two-way Radio MCU Ex: Operating voltage 3V, setup and enable the maximum modulation of the Sub-audio path, VR5=default(3FFh): Sub-audio path modulating flow: Flow description: <14082>：The CLI written ID. <104CB>：Select the register: 04CB <100FF>：Setup data: 00FFh. VR2 = FFh enables the maximum VR2 level.
  • Page 26 HT98R068 Two-way Radio MCU VOX Detect Status Chart In this mode, setup the slow mode, then lower the audio processor 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.
  • Page 27 HT98R068 Two-way Radio MCU (2) VOX Signal Status Detect: Flow description (1): <81EC7>：Enable the MIC and PGA circuits. 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 and the audio out to be DAC common-mode bias to reduce the noise.

  • Page 28: Parameter Setting

    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...
  • Page 29 HT98R068 Two-way Radio MCU Tool Note  Use the development tool specifically for the HT98R068. Real ICE ： MEV(Lot No.:M1001C)＋DEV(Lot No.:D1044A)  Some modifications should be made to the ICE circuit by adding a PLL Clock Sources (32.768 crystal) and a filter (PLLC Circuit). Check the figure below (please note the pin name and the circuit.
  • Page 30 HT98R068 Two-way Radio MCU ICE pin assignment vs. 48LQFP real chip： Real Real Real Real Real Real Chip Pin Real Chip Chip Real Chip Chip Chip Chip Chip Name Pin Name Pin Name Name PA7/RESB XOUT PLLC MIC_O MIC_I DEMOD...
  • Page 31 HT98R068 Two-way Radio MCU Appendix Different Functional Groups Audio Processor System Clock Speed Table. Sub-Audio Voice Band Scrambler Compandor Emphasis Fsys_Audo ˇ ˇ ˇ ˇ ˇ ˇ ˇ ˇ ˇ ˇ ˇ ˇ None ˇ ˇ ˇ ˇ ˇ ˇ...
  • Page 32 HT98R068 Two-way Radio MCU Fsys_Audo：Audio processor Fsys. Sub-Audio Voice Band Scrambler Compandor Emphasis Fsys_Audo ˇ ˇ ˇ ˇ ˇ ˇ ˇ ˇ ˇ ˇ ˇ ˇ None ˇ ˇ ˇ ˇ ˇ ˇ ˇ None ˇ ˇ ˇ ˇ ˇ...