Decouple hardware specific code from generic, agnostic code

2026-08-11 16:32:52 +00:00 · 2026-06-23 17:20:59 -07:00
parent fb130559e2
commit 0b0c9335f9
24 changed files with 768 additions and 910 deletions
@@ -0,0 +1,65 @@
+#ifndef TIMING_AVR_H
+#define TIMING_AVR_H
+
+// AVR ATtiny3216 timing parameters. Derives F_CPU (needed by avr-libc, e.g.
+// util/delay.h) and the bus-timer (TCB) tick period from the CMake-provided
+// FREQSEL / CLK_PRESCALE / TCB_CLKSEL, then hands the generic timing.h a TICK_US
+// (microseconds per TCB tick) so the physical bit-phase durations resolve to
+// TCB-tick counts. TICK_US == TCB_TICK / 1000, so every derived constant is
+// numerically identical to the previous F_CPU/TCB_CLKSEL formulation.
+
+#define __CLKCTRL_PDIV_2X_gc  2
+#define __CLKCTRL_PDIV_4X_gc  4
+#define __CLKCTRL_PDIV_8X_gc  8
+#define __CLKCTRL_PDIV_16X_gc 16
+#define __CLKCTRL_PDIV_32X_gc 32
+#define __CLKCTRL_PDIV_64X_gc 64
+#define __CLKCTRL_PDIV_6X_gc  6
+#define __CLKCTRL_PDIV_10X_gc 10
+#define __CLKCTRL_PDIV_12X_gc 12
+#define __CLKCTRL_PDIV_24X_gc 24
+#define __CLKCTRL_PDIV_48X_gc 48
+
+#if CLK_PRESCALE == 0x01
+  #define F_CPU     (FREQSEL / __CLK_PRESCALE_DIV)
+  #define CYCLE_MUL __CLK_PRESCALE_DIV
+#else
+  #define F_CPU     (FREQSEL)
+  #define CYCLE_MUL 1
+#endif
+
+// CPU_CYCLE / TCB_TICK are in nanoseconds.
+#if FREQSEL == 20000000L
+  #define CPU_CYCLE (50 * CYCLE_MUL)
+#elif FREQSEL == 16000000L
+  #define CPU_CYCLE (62.5 * CYCLE_MUL)
+#else
+  #error "Not implemented"
+#endif
+
+#ifndef TCB_CLKSEL_CLKDIV1_gc
+  #define TCB_CLKSEL_CLKDIV1_gc (0x00 << 1)
+#endif
+
+#ifndef TCB_CLKSEL_CLKDIV2_gc
+  #define TCB_CLKSEL_CLKDIV2_gc (0x01 << 1)
+#endif
+
+#ifndef TCB_CLKSEL_CLKTCA_gc
+  #define TCB_CLKSEL_CLKTCA_gc (0x02 << 1)
+#endif
+
+#if TCB_CLKSEL == TCB_CLKSEL_CLKDIV1_gc
+  #define TCB_TICK (CPU_CYCLE)
+#elif TCB_CLKSEL == TCB_CLKSEL_CLKDIV2_gc
+  #define TCB_TICK (CPU_CYCLE * 2)
+#elif TCB_CLKSEL == TCB_CLKSEL_CLKTCA_gc
+  #error "Not implemented"
+#endif
+
+// TCB_TICK is nanoseconds/tick; the generic timing.h wants microseconds/tick.
+#define TICK_US (TCB_TICK / 1000.0)
+
+#include "timing.h"
+
+#endif // TIMING_AVR_H