Preempt USB interrupt to read bytes in usbtiny

example/echodw/Makefile

@@ -0,0 +1,36 @@
+
+#MCU=attiny13
+#F_CPU = 9600000
+MCU=attiny84
+F_CPU = 8000000
+#MCU=attiny85
+#F_CPU = 1000000
+
+CFLAGS =
+CFLAGS += -Wno-deprecated-declarations
+CFLAGS += -Wl,--gc-sections
+CFLAGS += -fdata-sections -ffunction-sections
+COMPILE = avr-gcc -Wall -Os --std=c++11 -save-temps=obj -DF_CPU=$(F_CPU) $(CFLAGS) -mmcu=$(MCU)
+
+BASENAME = $(notdir $(PWD))
+OBJECTS = $(addsuffix .o, $(basename $(wildcard *.cpp)))
+
+all: $(BASENAME).elf
+
+dwload:
+	dwdebug l $(BASENAME).elf ,qr
+
+clean:
+	rm -f *.elf *.map *.o *.i *.ii *.s *.lss
+
+.cpp.o:
+	$(COMPILE) -c $< -o $@
+
+%.i: %.cpp
+	$(COMPILE) -E -c $< -o $@
+
+$(BASENAME).elf: $(OBJECTS)
+	$(COMPILE) -Wl,-Map,$(BASENAME).map -o $(BASENAME).elf $(OBJECTS)
+
+disasm:	$(BASENAME).elf
+	avr-objdump -d $(BASENAME).elf > $(BASENAME).lss

example/echodw/core.hpp

@@ -0,0 +1,20 @@
+// items used in assembler as well as C
+#ifndef MUAPK_EXP
+#define MUAPK_EXP(A) A
+#define MUAPK_INT(A0,A1) A0##A1
+#define MUAPK_CAT(A0,A1) MUAPK_INT(A0,A1)
+#define MUAPK_2_0(A0,A1) A0
+#define MUAPK_2_1(A0,A1) A1
+#define MUAPK_3_0(A0,A1,A2) A0
+#define MUAPK_3_1(A0,A1,A2) A1
+#define MUAPK_3_2(A0,A1,A2) A2
+#define MUAPK_4_0(A0,A1,A2,A3) A0
+#define MUAPK_4_1(A0,A1,A2,A3) A1
+#define MUAPK_4_2(A0,A1,A2,A3) A2
+#define MUAPK_4_3(A0,A1,A2,A3) A3
+#define MUAPK_5_0(A0,A1,A2,A3,A4) A0
+#define MUAPK_5_1(A0,A1,A2,A3,A4) A1
+#define MUAPK_5_2(A0,A1,A2,A3,A4) A2
+#define MUAPK_5_3(A0,A1,A2,A3,A4) A3
+#define MUAPK_5_4(A0,A1,A2,A3,A4) A4
+#endif // MUAPK_EXP

example/echodw/echodw.cpp

@@ -0,0 +1,27 @@
+
+#include "uartsoft.hpp"
+
+#include <avr/wdt.h>
+#include <string.h>
+#include <util/delay.h>
+
+int main() {
+  uartSoft.begin();
+
+  for (;;) {
+    wdt_reset();
+    _delay_ms(100);
+
+    // get the data
+    char* s;
+    uint8_t n = uartSoft.read(&s);
+    if (!n) continue;
+
+    // send it back
+    char buf[32] = "got: ";
+    strcat(buf, s);
+    strcat(buf, "\n");
+    _delay_ms(100);
+    uartSoft.write(buf, strlen(buf));
+  }
+}

example/echodw/rpc.hpp

@@ -0,0 +1,19 @@
+#ifndef rpc_hpp
+#define rpc_hpp
+
+#ifdef CORE_RPC_HPP
+#include "../core/rpc.hpp"
+#else
+
+#include <stdint.h>
+
+const uint8_t RpcPayloadMax = 0;
+const uint8_t RpcNumber = 0;
+struct RpcSend { };
+struct Rpc {
+  inline uint8_t Size(uint8_t i) { return 0; }
+  inline void VtAct(uint8_t i) { }
+};
+
+#endif // CORE_RPC_HPP
+#endif