AnyTone AT-D868UV a look inside
The back side of the GPS & LCD screen board. Ribbon cables removed for clarity. Note the mini GPS antenna to the right – it sits underneath the AnyTone badge above the display.
The 868 main board back side, with brass RF shield fitted
The 868 main board back side, with brass RF shield removed this time
The 868 main board front side
You can download higher resolution pictures of the main boards here:
Known bugs with the AT-D868UV:
May or may not apply to the DMR-6×2
The following is a list of bugs that I’m aware of with the AnyTone AT-D868UV under firmware 2.32. There may be other bugs not listed here, so it’s not an exhaustive list.
- An ’all call’ with talkgroup ID 16777215 shows in the Last Heard list as TG 20503
- Analogue transmissions with CTCSS using ’reverse tone burst’ for squelch tail elimination do not quietly mute reliably
- FM VFO only permits tuning from 87.5 to 108 MHz no matter what ’Mode’ the radio is set to, where as programming software allows 76.0 to 108.0 MHz to be programmed as a memory
- When starting up FM mode, the currently set volume level is ignored and the radio starts at a default (loud!) volume
General technical information
The AT-D868UV contains the following devices:
- GD32F303VTG6 ARM Cortex-M4 32 bit MCU with 1024kbyte flash and 96kbyte SRAM & 12.0 MHz oscillator
- Toshiba TC58CVG0S3HRAIG 1Gbit / 128Mbyte NAND flash memory
- Sicomm CT3258TD baseband processor for DMR & dPMR with built in AMBE2+ vocoder & 12.2 MHz oscillator
- Texas Instruments TLV320AIC3204 DSP / codec
- AT1846S radio-on-a-chip & 26.0 MHz reference oscillator
- RDA 5802N FM broadcast band receiver
- H&M Semiconductor HM8872 8 watt audio power amp
- NXP AFT05MS006NT1 LDMOS 6 watt RF power amp, 18dB narrowband gain, for independent VHF & UHF power amp stages
- 2SC3356 based low noise preamps for VHF & UHF receiver stages
- VHF and UHF receive front ends each have four stages of varactor track tuned filtering
- Infineon BGM781N11 GPS front end and ATGM336H GPS / GNSS positioning module (GPS models only)
- Battery backup for real time clock
- Solder pads for expansion memory SOIC size IC and a small push fit expansion connector for unknown device, appears tied in to MCU lines. Only found on version 2 hardware only?
Early investigations to flash memory structure in the AT-D868UV
may not apply to the 6×2
The 868 is fitted with a 128 Mbyte flash memory, along with another 1 Mbyte of flash memory in the MCU that holds the operating firmware. Here’s what I know about the structure of memory in the 868 so far:
0x00000000 to 0x07FFFFFF is mapped to external flash memory chip.
- Lower half of flash is used for codeplug storage & start up image bitmap
- 0x042C0000 to 0x042C9FFF is for start up image bitmap
- Upper half of flash holds the DMR ID database, actually less than half the flash is used for this! (Plenty of scope for expansion by database compression, more efficient use of memory etc.)
0x08000000 to 0x080FFFFF is mapped to MCU internal flash memory
- 0x08000000 to 0x08003FFF used by the 868 boot loader for firmware updating etc
- 0x08004000 to 0x0807FFFF used by firmware and display fonts
- 0x08080000 to 0x080FFFFF is empty
Future developments & ideas
- Exploring flash memory contents, where hidden data may reside, which is likely to include things such as ’soft’ RF alignment data, with the ultimate aim of producing a software tool to enable users to customise, align and maintain their own radio; for example setting low power at very low levels instead of 1 watt for hotspot use.
- Possible identification and modification of receive tracking gain scheme to improve sensitivity between 210 & 400 MHz
- Exploiting the capabilities of the TLV320AIC3204 audio codec chip inside the 868. This is a very powerful chip with the possible scope to facilitate DSP noise reduction, equalisation, tone control and digital AGC audio.
- Could the new 878 firmware be used in the 868 to give it extra features?
© Copyright Jason Reilly, 2018