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-rw-r--r--openpicc/timer-design.txt6
-rw-r--r--openpicc/timer.diabin0 -> 2631 bytes
2 files changed, 4 insertions, 2 deletions
diff --git a/openpicc/timer-design.txt b/openpicc/timer-design.txt
index 392d537..b56ded1 100644
--- a/openpicc/timer-design.txt
+++ b/openpicc/timer-design.txt
@@ -44,8 +44,10 @@ tc_cdiv: XC1=TCLK1 (in), TIOB0 (out), TIOA0 (out), XC2=TCLK2 (in)
RA = 1, RB = 1 + divider/2, RC = divider
i.o.w: when CV = 0 (either through swtrg or through RC compare) then TIOA0 and TIOB0 are clear
- TIOA0 is set on RA compare (at CV=1), is connected to XC2 (through TCLK2) and therefore triggers the external event which sets TIOB0
- TIOB0 is cleared at RB compare (at CV=1+divider/2)
+ TIOA0 is set on RA compare (at CV=1+phase), is connected to XC2 (through TCLK2) and therefore triggers the external event which sets TIOB0
+ TIOB0 is cleared at RB compare (at CV=1+divider/2+phase)
+ that means: Compare A sets TIOB and Compare B clears TIOB, Compare C is fixed at the divisor value, Compare A and B are divisor/2 apart, yielding an exact 50% duty cycle with a variable phase shift (offset from CV=0)
+ this trick is necessary because TIO{A,B} can't be directly affected by Compare {B,A}, so when using only one TIO you can either get a fixed duty cycle with zero offset compared to CV=0, or a variable offset yielding a variable duty cycle
tc_fdt: TIOA2 (out), TIOB2 (in), XC1=TCLK1 (in)
TC2 enabled
diff --git a/openpicc/timer.dia b/openpicc/timer.dia
new file mode 100644
index 0000000..406e22a
--- /dev/null
+++ b/openpicc/timer.dia
Binary files differ
personal git repositories of Harald Welte. Your mileage may vary