Boost "fixed" pw from OP1B in units with volt-ctrl-pw at low PRFs.

Makes PRF calibration work properly. Otherwise duty cycle is too low.

1 files changed, 24 insertions, 3 deletions

diff --git a/device-functions.c b/device-functions.c
index a0db6d9..5379741 100644
--- a/device-functions.c
+++ b/device-functions.c
@@ -455,13 +455,34 @@ int Set_Pw(int check_possible_only,int word_override,int range_override,int chan
 
 			/* use DAC8420 to control PW in lowest PW range */
 			if (!relay_range) {
+				// set the voltage to the actual PW-control circuit (normally in a module)
 				set_dac(globals.Flash.pw_dac[channel],word_out);
+
+				// This word is fed to the PW circuit on the OP1B board, not the module
+				// Set to a fixed value. Isn't actually used to control PW in this mode,
+				// but triggers following stages.
 				word_out=globals.Flash.fix_pw_dac_val[channel];
-				/* Set to fixed value. */
-				/* Isn't actually used to control PW in this mode, but may trigger following stages */
 
-				/* Zout hardware/software is used in AVPP to control PW ranges, not Zout */
+				// Also, boost the internal PW range so that PRF calibration works at
+				// low PRFs (i.e., reasonable duty cycle for scope to see).
+				// Bit of a hack based on the period.
+				int rough_range = ((int) log10 (1.0/globals.ChannelState[channel].frequency)) + 6;
+				if (rough_range < 0) {
+					rough_range = 0;
+				}
+				if (rough_range >= timing_ranges) {
+					rough_range = timing_ranges-1;
+				}
+			        if (rough_range==0) {
+			                cap_range_control=0;
+			        } else {
+			                cap_range_control = 1 << (rough_range-1);
+			        }
+
+				/* Zout hardware/software is used in AVPP to control PW ranges in the
+ * 				   external circuitry, not Zout */
 				Set_zout(channel,globals.Flash.zout_min[channel],0);
+
 			} else {
 				Set_zout(channel,globals.Flash.zout_max[channel],0);