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Add opt-in support for "LED_ENABLED" feature #15

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Merged
volium merged 3 commits into from
Feb 11, 2022
Merged

Add opt-in support for "LED_ENABLED" feature #15

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e3cf9e1
Add opt-in support for "LED_ENABLED" feature
Jan 20, 2022
c82b526
Address feedback from Osamu
Jan 24, 2022
00bf03f
Save 2 bytes in the watchdog handling code
sigprof Aug 20, 2021
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138 changes: 96 additions & 42 deletions nanoBoot.S
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Original file line number Diff line number Diff line change
Expand Up @@ -48,34 +48,77 @@
; hfuse memory = 0xDF
; efuse memory = 0xC4

; LED -- Configure this for the LED
;
; Teensy 2.0 compatible board (Adjust for other board)

; ==========================================================
; LED SUPPORT START

; Turn LED on while bootloader is active
; NOTE: This feature uses 6 bytes for active high and 8 bytes for active low;
; see "Enable LED" in the "run_bootloader" section for details.

; Uncomment the following line to enable LED feature
; #define LED_ENABLED

; LED Configuration
; Uncomment or add a new LED configuration for your specific board

; Adafruit's Atmega32u4 Breakout Board (Product ID: 296) - Now discontinued
; https://www.adafruit.com/product/296
; -- LED is ON with ATmega32u4 PIN E6 HIGH
; #define LED_BIT 6
; #define LED_CONF DDRE
; #define LED_PORT PORTE
; #define LED_ACTIVE_LEVEL 1

; Teensy 2.0 compatible board
; -- LED is ON with ATmega32u4 PIN D6 HIGH
#define LED_BIT 6
#define LED_CONF DDRD
#define LED_PORT PORTD
; #define LED_BIT 6
; #define LED_CONF DDRD
; #define LED_PORT PORTD
; #define LED_ACTIVE_LEVEL 1

; Leonardo/Nano compatible board (Adjust for other board)
; Leonardo/Nano compatible board
; -- LED is ON with ATmega32u4 PIN C7 HIGH
; #define LED_BIT 7
; #define LED_CONF DDRC
; #define LED_PORT PORTC
; #define LED_BIT 7
; #define LED_CONF DDRC
; #define LED_PORT PORTC
; #define LED_ACTIVE_LEVEL 1

; Pro Micro compatible board (Adjust for other board)
; Pro Micro compatible board
; -- LED is ON with ATmega32u4 PIN D5 LOW
; #define LED_BIT 5
; #define LED_CONF DDRD
; #define LED_PORT PORTD
; #define LED_BIT 5
; #define LED_CONF DDRD
; #define LED_PORT PORTD
; #define LED_ACTIVE_LEVEL 0

; Pro Micro compatible board (Adjust for other board)
; Pro Micro compatible board
; -- LED is ON with ATmega32u4 PIN B3 LOW
; #define LED_BIT 3
; #define LED_CONF DDRB
; #define LED_PORT PORTB
; #define LED_BIT 3
; #define LED_CONF DDRB
; #define LED_PORT PORTB
; #define LED_ACTIVE_LEVEL 0

#if defined(LED_ENABLED)
#if !defined(LED_PORT) || !defined(LED_CONF) || !defined(LED_BIT) || !defined(LED_ACTIVE_LEVEL)
#error "If LED feature is enabled, the following need to be defined: LED_BIT, LED_CONF, LED_PORT, LED_ACTIVE_LEVEL"
#else
; Set IO register as output for LED
#define ENABLE_LED_OUTPUT sbi _SFR_IO_ADDR(LED_CONF), LED_BIT
#if LED_ACTIVE_LEVEL == 1
#define TURN_LED_ON sbi _SFR_IO_ADDR(LED_PORT), LED_BIT
#define TURN_LED_OFF cbi _SFR_IO_ADDR(LED_PORT), LED_BIT
#elif LED_ACTIVE_LEVEL == 0
#define TURN_LED_ON cbi _SFR_IO_ADDR(LED_PORT), LED_BIT
#define TURN_LED_OFF sbi _SFR_IO_ADDR(LED_PORT), LED_BIT
#else
#error "LED_ACTIVE_LEVEL needs to be either 1 (active high) or 0 (active low)"
#endif
#endif
#endif

; LED SUPPORT END
; ==========================================================

; Except for Pro Micro compatible board, initially LED is off.
; This code assumes Teensy 2.0 or Leonardo/Nano compatible board

; SW assumptions:
; The bootloader only "needs" endpoint 0; however, the HID spec requires any HID device to have an
Expand Down Expand Up @@ -162,9 +205,6 @@
# define BOOT_ADDRESS 0
#endif

; For debugging purposes
.equ LED_PIN, 6

.section .vectors

; We still want the reset vector to jump to "main"
Expand Down Expand Up @@ -343,12 +383,9 @@ main:

; We MUST disable the Watchdog Timer first, otherwise it will remain enabled and will keep resetting the system, so...
; Disable Watchdog Timer
ldi r16, _BV(WDCE) | _BV(WDE) ; Load r16 with the value needed to "unlock" the Watchdog Timer Configuration
; Write a logic one to the Watchdog Change Enable bit (WDCE) and Watchdog System Reset Enable (WDE)

mov r17, rZERO ; Load r17 with zero to disable the Watchdog Timer completely

rcall set_watchdog_timer ; Call the subroutine that sets the watchdog timer with the values loaded in r16 and r17
rcall set_watchdog_timer ; Call the subroutine that sets the watchdog timer with the value loaded in r17

; check_reset_flags:
sbrs rMCUSR, EXTRF ; Skip the next instruction if EXTRF is set (if External Reset Flag, skip next instruction, go to run_bootloader)
Expand All @@ -357,11 +394,21 @@ run_application: ; We get here if the cause of th
jmp 0 ; Simply jump to 0x0000 (application) IMPORTANT NOTE!! This CANNOT be an 'rjmp'!!

run_bootloader:
sbi _SFR_IO_ADDR(LED_CONF), LED_BIT ; Set IO register as output for LED
; No need to trun off LED initially (non-promicro) -- MCU port is initialized as 0
;sbi _SFR_IO_ADDR(LED_PORT), LED_BIT ; Trun off LED initially (promicro)
set ; Initialize BootLoaderActive flag (T flag in SREG)

; Enable LED
#if defined(LED_ENABLED)
; Set IO register as output for LED
ENABLE_LED_OUTPUT

; If the LED is active low, we need to turn it off here (set LED_BIT) since the MCU IO port is
; initialized as 0. This is a 2-byte penalty when using active low LED.
#if LED_ACTIVE_LEVEL == 0
TURN_LED_OFF
#endif
#endif



; =================================================================
; = Setup IRQ Vector Table
Expand Down Expand Up @@ -551,23 +598,22 @@ exit_bootloader:
ori r16, _BV(DETACH) ; Set the DETACH bit to enable the detachment
std Y+oUDCON, r16 ; Store r16 to the USB Device Configuration Register (UDCON)

#if defined(LED_ENABLED)
; Turn LED off before exiting
TURN_LED_OFF
#endif

; =================================================================
; = Watchdog Timer initialization
; =================================================================

cbi _SFR_IO_ADDR(LED_PORT), LED_BIT ; Trun off LED before exiting (non-promicro)
;sbi _SFR_IO_ADDR(LED_PORT), LED_BIT ; Trun off LED before exiting (promicro)

; NOTE!! This part of the code assumes MCUSR has already been cleared

; Enable WDT, ~250 ms timeout (force a timeout to reset the AVR)
ldi r16, _BV(WDCE) | _BV(WDE) ; Load r16 with the value needed to "unlock" the Watchdog Timer Configuration
; Write a logic one to the Watchdog Change Enable bit (WDCE) and Watchdog System Reset Enable (WDE)

ldi r17, _BV(WDE) | _BV(WDP2) ; Load r17 with the value needed to set the desired Watchdog Configuration (WDCE = 0, not set!)
; Write the WDE and Watchdog prescaler bits (WDP); System Reset Mode (WDE = 1) and ~250 ms timeout (WDP2 = 1)

rcall set_watchdog_timer ; Call the subroutine that sets the wathdog timer with the values loaded in r16 and r17
rcall set_watchdog_timer ; Call the subroutine that sets the watchdog timer with the value loaded in r17

; for (;;);
final_loop:
Expand Down Expand Up @@ -719,6 +765,14 @@ HANDLE_USB_STANDARD_DEVICE:
; fallthrough to SET_CONFIGURATION if equal
SET_CONFIGURATION:

#if defined(LED_ENABLED)
; Turn LED on towards the end of enumeration (SET_CONFIGURATION is done after SET_ADDRESS)
; TODO: If we ever have space, we could add a flag here to mark the fact that we have entered
; this state, and turn the LED on at the end of the setup request. For now this is the best we
; can do.
TURN_LED_ON
#endif

; Optimization by "sigprof" that saves 2 bytes
; Dirty trick: We don't need to do anything for SET_CONFIGURATION except process_Host2Device,
; so we reuse the SET_ADDRESS code by making it reload the same value to UDADDR.
Expand Down Expand Up @@ -937,9 +991,6 @@ verifyMaxDescriptorLength:

send_descriptor:

sbi _SFR_IO_ADDR(LED_PORT), LED_BIT ; Trun on LED before exiting (non-promicro)
;cbi _SFR_IO_ADDR(LED_PORT), LED_BIT ; Trun on LED before exiting (promicro)

; Abort if RXSTPI is set
ldd r17, Y+oUEINTX ; Load r17 with the value in the USB Endpoint Interrupt Register (UEINTX);
sbrc r17, RXSTPI ; Skip the next instruction if the Received SETUP Interrupt Flag (RXSTPI) is cleared
Expand Down Expand Up @@ -1020,8 +1071,11 @@ EP_ISR_END:

set_watchdog_timer:

; IMPORTANT!! This function assumes the correct values for the WDTCSR register
; configuration are already loaded onto r16 and 17.
; IMPORTANT!! This function assumes the correct value for the WDTCSR register
; configuration is already loaded onto r17; it also modifies r16.

ldi r16, _BV(WDCE) | _BV(WDE) ; Load r16 with the value needed to "unlock" the Watchdog Timer Configuration
; Write a logic one to the Watchdog Change Enable bit (WDCE) and Watchdog System Reset Enable (WDE)

wdr ; Reset the Watchdog Timer

Expand Down