From 514ff44d311ccff78ace88f038a08bb084bc9270 Mon Sep 17 00:00:00 2001
From: Sergey Yarkov <serzh.yarkov@gmail.com>
Date: Sun, 26 Sep 2021 16:45:17 +0300
Subject: [PATCH] refactor: makefile & blink program

---
 Makefile     | 10 ++++++--
 firmware.asm | 71 ++++++++++++++++++++++++++--------------------------
 firmware.hex |  9 +++----
 3 files changed, 47 insertions(+), 43 deletions(-)

diff --git a/Makefile b/Makefile
index 68c3f63..7fba996 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,13 @@
+MCU = t24
 SRCFILE = firmware
- 
-compile: $(SRCFILE).asm
+TARGET = usbasp
+DEVICE = usb
+
+build: $(SRCFILE).asm
 	gavrasm $(SRCFILE)
+
+flash:
+	avrdude -p $(MCU) -c $(TARGET) -P $(DEVICE) -U flash:w:$(SRCFILE).hex:a
  
 clean:
 	rm -f $(SRCFILE).asm~ $(SRCFILE).hex $(SRCFILE).obj $(SRCFILE).lst $(SRCFILE).cof
\ No newline at end of file
diff --git a/firmware.asm b/firmware.asm
index 38c42a8..bad8ae5 100644
--- a/firmware.asm
+++ b/firmware.asm
@@ -3,16 +3,16 @@
 ; Description: Blink an led every one second
 ; Source code: https://github.com/sergeyyarkov/attiny24a_led-blink-example
 ; Device: ATtiny24A
-; Package: 14-pin-PDIP/SOIC
+; Package: 14-pin-PDIP_SOIC
 ; Assembler: gavrasm v5.0
 ;
 ; Written by Sergey Yarkov 23.09.2021
 
-.device ATtiny24A
+.device ATtiny24A           ; Setup device name
 .list                       ; Enable listing
 
 .macro init_stack_p         ; Setup stack pointer
-  ldi @0, low(@1),
+  ldi @0, low(@1)
   out SPL, @0
 .endm
 
@@ -20,7 +20,8 @@
 .equ LED_PORT = PORTA       ; LED Port
 .equ LED_PIN = PINA0        ; LED Pin
 
-.equ iVal = 65000
+.equ oVal = 20             ; If set to 0, then this value is decremented to 255
+.equ iVal = 10000           ; Value of cycles in inner delay loop
 
 .org 0x00                   ; Start program at 0x00
 .cseg                       ; Code segment
@@ -28,45 +29,43 @@
 main:                       ; Start up program
   init_stack_p r16, RAMEND
   rcall init_ports          ; Initialize MCU ports
-  rcall delay_loop_reset
+  rcall _r_inner_delay_loop ; Initialize delay inner loop value
+  rcall _r_outer_delay_loop           ; Intialize delay outer loop value
 
 loop:                       ; Program loop
-  cbi LED_PORT, LED_PIN
-  rcall delay_loop
-  sbi LED_PORT, LED_PIN
-  rcall delay_loop
-  rjmp loop
+  rcall toggle_led          ; Toggle an LED
+  rcall delay_1s            ; Delay for 1 sec
+  rjmp loop                 ; Jump to program loop again
 
-init_ports:                 ; Init MCU ports
-  ldi r16, (1<<LED_PIN)
-  ldi r17, (0<<LED_PIN)
-  nop
-  out LED_DIR, r16
-  out LED_PORT, r17
+toggle_led:                 ; Toggle an LED
+  eor r17, r16              ; Toggle bit
+  out LED_PORT, r17         ; Update port of LED
 ret
 
-delay_loop_reset:           ; Load value to registar pair again
+init_ports:                 ; Init MCU ports
+  ldi r16, (1<<LED_PIN)     ; Load to r16 high bit
+  out LED_DIR, r16          ; Set LED direction to output
+ret
+
+delay_1s_outer_l:
+  rcall _r_inner_delay_loop
+
+delay_1s:
+  sbiw r24, 1               ; Decrement inner loop value
+  brne delay_1s             ; Jump to inner loop again
+
+  rcall _r_inner_delay_loop ; Reset inner loop value
+
+  dec r18                   ; Decremnt outer loop value
+  brne delay_1s_outer_l     ; Jump to outer loop again
+  rcall _r_outer_delay_loop
+ret
+
+_r_inner_delay_loop:        ; Reset inner delay loop
   ldi r24, low(iVal)
   ldi r25, high(iVal)
 ret
 
-delay_loop:
-  sbiw r24, 1
-  brne delay_loop
-  nop
-  rcall delay_loop_reset
-  rcall delay_loop_2
-ret
-
-delay_loop_2:
-  sbiw r24, 1
-  brne delay_loop_2
-  rcall delay_loop_reset
-  rcall delay_loop_3
-ret
-
-delay_loop_3:
-  sbiw r24, 1
-  brne delay_loop_3
-  rcall delay_loop_reset
+_r_outer_delay_loop:        ; Reset outer delay loop
+  ldi r18, oVal
 ret
\ No newline at end of file
diff --git a/firmware.hex b/firmware.hex
index 30f1af6..1d41c53 100644
--- a/firmware.hex
+++ b/firmware.hex
@@ -1,7 +1,6 @@
 :020000020000FC
-:100000000FED0DBF06D00BD0D8980CD0D89A0AD0DF
-:10001000FBCF01E010E000000ABB1BBB089588EE97
-:100020009DEF08950197F1F70000F9DF01D00895E1
-:100030000197F1F7F4DF01D008950197F1F7EFDFB1
-:02004000089521
+:100000000FED0DBF08D012D014D002D008D0FDCF14
+:1000100010271BBB089501E00ABB089507D0019784
+:10002000F1F704D02A95D1F704D0089580E197E242
+:06003000089524E108958B
 :00000001FF