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--- atsmini:index [2026/07/08 15:33] – created natalie
+++ atsmini:index [2026/07/13 19:05] (current) – natalie
@@ Line 2: / Line 2: @@
 Got mine 2026/07/08, AMNVOLT ATS MINI V4 metal shell version. Allegedly V4b according to Amazon listing.
-===== Info =====
+===== Firmware =====
+  * [[https://github.com/ralphxavier/SI4735|SI4735 by Ralph Xavier]] - as far as I can tell this is the most OG of all firmware, although it is not compatible with the ATS MINI units...?
+  * [[https://oshwhub.com/sunnygold/esp32s3-si4732-shou-yin-ji|Sunnygold firmware]] - based on the above, modified by the original developer of these units
+  * [[https://github.com/pu2clr/SI4735|PU2CLR SI4735 library]]
+  * [[https://github.com/goshante/ats20_ats_ex|ats20_ats_ex]]
+  * [[https://github.com/G8PTN/ATS_MINI|G8PTN ATS_MINI]] - based on the Sunnygold and Goshante firmware
+  * [[https://github.com/esp32-si4732/ats-mini|ats-mini by Max Arnold]] - based on the above
+  * [[http://www.hjberndt.de/dvb/pocketSI4735DualCoreDecoder.html|H.-J. Berndt firmware]] - closed source, boo!
+Some of the info about the lineage of the various firmware projects here may be incorrect.
+Mine came with v2.33 of the Max Arnold firmware.
+===== MCU Info =====
 ==== read_flash_status ====
 <code>
@@ Line 224: / Line 236: @@
 Flash voltage (VDD_SPI) set to 3.3V by efuse.
 </code>
+===== Audio Readback =====
+V4b units have the audio output (speaker, not headphones, see below!) connected to ESP IO11.
+From what I gather, this was originally a common mod (popularized by the H.-J. Berndt firmware?) which was then integrated into the V4b production PCBs. This is connected somewhere around the speaker PA - not sure if before or after the amp, although presumably before, since the amp should be able to swing up to VCC_BAT which can be over 3.3v. As such, it is **not usable** when headphones are plugged in, as the headphone jack switch interrupts the signal to the speaker PA*
+*TODO: Need to verify this on V4b since it has a headphone amp which is not present on the original. The mechanism by which the speaker is disabled may be different. Regardless it is still not usable when headphones are plugged in on V4b
+===== Headphone Amp =====
+LM4809
+===== FM Stereo =====
+Why is the sound mono despite having a strong signal with the stereo indicator lit?
+Not a hardware fault, the two discrete paths from tuner -> HPA -> headphone jack are fine.
+Seems default FM stereo blend settings on tuner are much too conservative. Needs further experimentation.
 ===== Files =====
-{{ :atsmini:atsmini.bin |Stock firmware entire flash dump}}
+{{ :atsmini:atsmini.bin |V4b stock firmware entire flash dump}}