tnt has uploaded this change for review. ( https://gerrit.osmocom.org/c/osmo-e1-hardware/+/29608 )

Change subject: icE1usb fw/gpsdo: Use a struct for VCTXO dependent params ......................................................................

icE1usb fw/gpsdo: Use a struct for VCTXO dependent params

Not that useful for now, but prep for PID loop

Signed-off-by: Sylvain Munaut tnt@246tNt.com Change-Id: Iffea8992130eccd98a2952b08277e3d0d2568a1f --- M firmware/ice40-riscv/icE1usb/gpsdo.c 1 file changed, 23 insertions(+), 15 deletions(-)

git pull ssh://gerrit.osmocom.org:29418/osmo-e1-hardware refs/changes/08/29608/1

diff --git a/firmware/ice40-riscv/icE1usb/gpsdo.c b/firmware/ice40-riscv/icE1usb/gpsdo.c index 477d2e7..5975100 100644 --- a/firmware/ice40-riscv/icE1usb/gpsdo.c +++ b/firmware/ice40-riscv/icE1usb/gpsdo.c @@ -17,6 +17,9 @@

struct { + /* Configuration */ + enum gpsdo_vctxo_model vctxo; + /* Current tuning */ struct { uint16_t coarse; @@ -41,7 +44,6 @@

/* Coarse tuning */ struct { - int vctxo_sensitivity; int step; } coarse;

@@ -54,19 +56,25 @@ } g_gpsdo;

-/* VCXTO sensitivity vs 'coarse' count for fast initial acquisition */ - /* - * Note that the spec if often a guaranteed minimum range and goes - * from ~0.1V to 3.2V instead of 0-3.3V so actual sensitivity is - * higher than the "theoritical value". We boost it by ~ 10% here. - */ -static const int -vctxo_sensitivity[] = { - /* +- 50 ppm pull range => ~ 0.75 Hz / hi-count (set to 0.85) */ - [VCTXO_TAITIEN_VT40] = 300, +/* + * VCXTO parameters + * + * - iKv is reciprocal sensitivity vs 'coarse' count for fast initial acquisition + * + * Note that the spec if often a guaranteed minimum range and goes + * from ~0.1V to 3.2V instead of 0-3.3V so actual sensitivity is + * higher than the "theoritical value". We boost it by ~ 10% here. + */ +static const struct { + int iKv; /* hi-count / Hz (.8 fixed point) */ +} vctxo_params[] = { + [VCTXO_TAITIEN_VT40] = { + .iKv = 300, /* +- 50 ppm pull range => ~ 0.75 Hz / hi-count (set to 0.85) */ + },

- /* +- 100 ppm pull range => ~ 1.50 Hz / hi-count (set to 1.6) */ - [VCTXO_SITIME_SIT3808_E] = 160, + [VCTXO_SITIME_SIT3808_E] = { + .iKv = 160, /* +- 100 ppm pull range => ~ 1.50 Hz / hi-count (set to 1.6) */ + }, };

/* Tuning params */ @@ -195,7 +203,7 @@ }

/* Estimate correction and apply it */ - g_gpsdo.tune.coarse -= (freq_diff * g_gpsdo.coarse.vctxo_sensitivity) >> 8; + g_gpsdo.tune.coarse -= (freq_diff * vctxo_params[g_gpsdo.vctxo].iKv) >> 8; pdm_set(PDM_CLK_HI, true, g_gpsdo.tune.coarse, false);

/* Skip next measurement */ @@ -357,5 +365,5 @@

/* Initial state and config */ g_gpsdo.state = STATE_HOLD_OVER; - g_gpsdo.coarse.vctxo_sensitivity = vctxo_sensitivity[vctxo]; + g_gpsdo.vctxo = vctxo; }