--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/compal/audio/omr-from-ds	Tue Nov 09 18:49:09 2021 +0000
@@ -0,0 +1,140 @@
+On 2021-11-09 long-time FreeCalypso community member Das Signal contributed a
+set of omr readouts from a C139 phone operating in handheld (as opposed to
+headset) audio mode, made by way of wires soldered to UART connection pads
+inside the battery compartment.  Raw data here:
+
+https://www.freecalypso.org/pipermail/community/2021-November/000829.html
+
+The post from DS includes only fc-tmsh output but not command input;
+for better readability and understanding, here are the same readouts
+interleaved with the commands that produced them:
+
+- before the call
+
+>omr ffd001ec 2
+omr 00:  90 02
+>omr ffd001d6 2
+omr 00:  16 00
+>omr ffd001dc 4
+omr 00:  8E 01 8C 19
+>omr ffd00238 2
+omr 00:  C7 03
+>omr ffd0084a 10
+omr 00:  01 00 14 00 CC 4C AD 59  00 75 00 00 00 10 00 10
+>omr ffd00908 3e
+omr 00:  00 40 00 00 00 00 00 00  00 00 00 00 00 00 00 00
+omr 10:  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00
+omr 20:  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00
+omr 30:  00 00 00 00 00 00 00 00  00 00 00 00 00 00
+>omr ffd00946 3e
+omr 00:  E7 FF 22 00 35 00 F1 FF  09 00 FF FF 80 FF 23 00
+omr 10:  BD FF 40 00 2A 01 BD FF  C1 03 09 01 1D E1 8F 3F
+omr 20:  1D E1 09 01 C1 03 BD FF  2A 01 40 00 BD FF 23 00
+omr 30:  80 FF FF FF 09 00 F1 FF  35 00 22 00 E7 FF
+
+- during the call
+
+>omr ffd001ec 2
+TM3 memread error: 41 0F 4E
+>omr ffd001d6 2
+omr 00:  16 00
+>omr ffd001dc 4
+omr 00:  0E 6A 4C 0A
+>omr ffd00238 2
+omr 00:  46 02
+>omr ffd0084a 10
+omr 00:  01 00 14 00 CC 4C AD 59  00 75 00 00 00 10 00 10
+>omr ffd00908 3e
+omr 00:  00 40 00 00 00 00 00 00  00 00 00 00 00 00 00 00
+omr 10:  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00
+omr 20:  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00
+omr 30:  00 00 00 00 00 00 00 00  00 00 00 00 00 00
+>omr ffd00946 3e
+omr 00:  E7 FF 22 00 35 00 F1 FF  09 00 FF FF 80 FF 23 00
+omr 10:  BD FF 40 00 2A 01 BD FF  C1 03 09 01 1D E1 8F 3F
+omr 20:  1D E1 09 01 C1 03 BD FF  2A 01 40 00 BD FF 23 00
+omr 30:  80 FF FF FF 09 00 F1 FF  35 00 22 00 E7 FF
+
+- after the call
+
+>omr ffd001ec 2
+omr 00:  90 02
+>omr ffd001d6 2
+omr 00:  16 00
+>omr ffd001dc 4
+omr 00:  CE 62 4C 1A
+>omr ffd00238 2
+omr 00:  C7 03
+>omr ffd0084a 10
+omr 00:  01 00 14 00 CC 4C AD 59  00 75 00 00 00 10 00 10
+>omr ffd00908 3e
+omr 00:  00 40 00 00 00 00 00 00  00 00 00 00 00 00 00 00
+omr 10:  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00
+omr 20:  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00
+omr 30:  00 00 00 00 00 00 00 00  00 00 00 00 00 00
+>omr ffd00946 3e
+omr 00:  E7 FF 22 00 35 00 F1 FF  09 00 FF FF 80 FF 23 00
+omr 10:  BD FF 40 00 2A 01 BD FF  C1 03 09 01 1D E1 8F 3F
+omr 20:  1D E1 09 01 C1 03 BD FF  2A 01 40 00 BD FF 23 00
+omr 30:  80 FF FF FF 09 00 F1 FF  35 00 22 00 E7 FF
+
+Analysis:
+
+Read of d_vbctrl1 during the call failed for some reason (the returned error
+code is E_CHECKSUM - perhaps the TM3 omr command packet got corrupted?),
+whereas before and after the call we got 0x0290.  Shifting right by 6 bits, we
+get 0x00A as the actual VBCTRL1 register value.  This reading is indeed
+consistent with handheld audio mode, as opposed to headset.
+
+d_vbctrl2: we got 0x0016 on all 3 reads.  Shifting right by 6 bits, we get 0x000
+as the actual VBCTRL2 register value.  This reading is once again consistent
+with handheld audio mode.
+
+d_vbuctrl: we got 0x018E before the call, 0x6A0E during the call and 0x62CE
+after the call.  The corresponding VBUCTRL register values are 0x006, 0x1A8 and
+0x18B, respectively.  Tabulating:
+
+Time point	d_vbuctrl	VBUCTRL		Sidetone	UL PGA
+----------------------------------------------------------------------
+before the call	0x018E		0x006		-5 dB		0 dB
+during the call	0x6A0E		0x1A8		-23 dB		2 dB
+after the call	0x62CE		0x18B		-20 dB		5 dB
+
+d_vbdctrl: we got 0x198C before the call, 0x0A4C during the call and 0x1A4C
+after the call.  The corresponding VBDCTRL register values are 0x066, 0x029 and
+0x069, respectively.  Tabulating:
+
+Time point	d_vbdctrl	VBDCTRL		Volume ctrl	DL PGA
+----------------------------------------------------------------------
+before the call	0x198C		0x066		-6 dB		0 dB
+during the call	0x0A4C		0x029		0 dB		3 dB
+after the call	0x1A4C		0x069		-6 dB		3 dB
+
+d_aec_ctrl: got 0x0246 during the call or 0x03C7 outside of a call.
+
+AEC parameter words: same as in the headset mode, no change with call state.
+
+AEC configuration appears to be almost exactly the same between handheld and
+headset modes, the only difference being in the NS level bits (d_aec_ctrl[6:5]):
+0x40 in handheld mode, 0x20 in headset mode.
+
+UL FIR coefficients: identity transform.
+
+DL FIR coefficients: got an actual filter this time, no change with call state:
+
+omr 00:  E7 FF 22 00 35 00 F1 FF  09 00 FF FF 80 FF 23 00
+omr 10:  BD FF 40 00 2A 01 BD FF  C1 03 09 01 1D E1 8F 3F
+omr 20:  1D E1 09 01 C1 03 BD FF  2A 01 40 00 BD FF 23 00
+omr 30:  80 FF FF FF 09 00 F1 FF  35 00 22 00 E7 FF
+
+Translating into 16-bit words:
+
+0xFFE7 0x0022 0x0035 0xFFF1 0x0009 0xFFFF 0xFF80 0x0023
+0xFFBD 0x0040 0x012A 0xFFBD 0x03C1 0x0109 0xE11D 0x3F8F
+0xE11D 0x0109 0x03C1 0xFFBD 0x012A 0x0040 0xFFBD 0x0023
+0xFF80 0xFFFF 0x0009 0xFFF1 0x0035 0x0022 0xFFE7
+
+The same extracted coefficients have been written into handheld-dl-fir in the
+format accepted by fir2freq analysis tool.  For the nsteps argument to fir2freq,
+I usually specify 40, so that the frequency response is computed in 100 Hz
+steps.