From 939a1da9e65f380de3889d644e8ff8dbf90797e9 Mon Sep 17 00:00:00 2001
From: Virgil Dupras <hsoft@hardcoded.net>
Date: Tue, 28 Jul 2020 16:29:10 -0400
Subject: [PATCH] recipes/arduinouno/at28: add companion at28dump program

---
 recipes/arduinouno/at28/Makefile     |   4 +-
 recipes/arduinouno/at28/at28dump.asm | 139 +++++++++++++++++++++++++++++++++++
 2 files changed, 141 insertions(+), 2 deletions(-)
 create mode 100644 recipes/arduinouno/at28/at28dump.asm

diff --git a/recipes/arduinouno/at28/Makefile b/recipes/arduinouno/at28/Makefile
index fa9668a..1cad12a 100644
--- a/recipes/arduinouno/at28/Makefile
+++ b/recipes/arduinouno/at28/Makefile
@@ -13,8 +13,8 @@ AVRA = avra
 all: $(TARGET)
 	@echo Done!
 
-send: $(PROGNAME).hex
-	avrdude $(AVRDUDEARGS) -p $(AVRDUDEMCU) -U flash:w:$(PROGNAME).hex
+send: $(TARGET)
+	avrdude $(AVRDUDEARGS) -p $(AVRDUDEMCU) -U flash:w:$(TARGET)
 
 $(TARGET): $(PROGNAME).asm
 	$(AVRA) -o $@ $(PROGNAME).asm
diff --git a/recipes/arduinouno/at28/at28dump.asm b/recipes/arduinouno/at28/at28dump.asm
new file mode 100644
index 0000000..5fd80dd
--- /dev/null
+++ b/recipes/arduinouno/at28/at28dump.asm
@@ -0,0 +1,139 @@
+; Use this as a debug companion to at28wr. This simply dumps, TTY-escaped, the
+; contents of the AT28.
+;
+; TODO: not always, but sometimes, the output starts with a spurious 0xFF. But
+; otherwise, the rest of the contents is good, albeit offset by 1 (that is, the
+; byte after the spurious 0xFF is the contents at addr 0). Weird, to fix.
+
+.include "m328Pdef.inc"
+
+; *** Pins ***
+.equ SRCP = PORTB2
+.equ SRDS = PORTB1
+.equ FLWE = PORTB3
+.equ FLOE = PORTB4
+.equ FLCE = PORTB5 ; WARNING: same as LED
+
+; *** Consts ***
+.equ BAUD_PRESCALE = 103	; 9600 bauds at 16mhz
+
+rjmp    main
+
+; *** Code ***
+; Sends char in r20 to UART
+; Perform TTY-escape transparently.
+uartwr:
+	lds	r16, UCSR0A
+	sbrs    r16, UDRE0	; wait until send buffer is empty
+	rjmp	uartwr
+	; should we escape?
+	cpi	r20, 0x21
+	brsh	uartwr_0	; r20 >= 0x21, skip
+	; escape
+	ori	r20, 0x80
+	ldi	r16, 0x20
+	sts	UDR0, r16
+	rjmp	uartwr
+uartwr_0:
+	sts	UDR0, r20
+	ret
+
+; send r23 to addr shift register.
+; We send highest bits first so that Q7 is the MSB and Q0 is the LSB
+sendaddr:
+	ldi	r16, 8		; we will loop 8 times
+	cbi	PORTB, SRDS
+	sbrc	r23, 7		; if latest bit isn't cleared, set SER_DP high
+	sbi	PORTB, SRDS
+	; toggle SRCP, not waiting between pulses. The CD74AC164 at 5V has a
+        ; 5.9ns CP min pulse width. We can't match that at 16mhz. No need to
+	; wait.
+	cbi	PORTB, SRCP
+	sbi	PORTB, SRCP
+	lsl	r23		; shift our data left
+	dec	r16
+	brne	sendaddr+1	; not zero yet? loop! (+1 to avoid reset)
+	ret
+
+; push r20 to the rom and increase the memory counter
+nextaddr:
+	; first, set up addr
+	mov	r23, r21
+	rcall	sendaddr
+	mov	r23, r22
+	rcall	sendaddr
+	inc	r22
+	brne	nextaddr_0	; no overflow? skip
+	inc	r21
+nextaddr_0:
+	ret
+
+; read EEPROM's I/O7:0 through PD7:2 and PB1:0 into r20
+readdata:
+	cbi	PORTB, FLCE
+	cbi	PORTB, FLOE
+	nop 			; 70ns max delay on at28
+	nop
+	nop
+	nop
+	; read bits 7:2
+	in	r20, PIND
+	andi	r20, 0xfc
+	; read bits 1:0
+	in	r16, PINB
+	andi	r16, 0x03
+	or	r20, r16
+	sbi	PORTB, FLOE
+	sbi	PORTB, FLCE
+	ret
+
+; Set PD7:2 and PB1:0 to output
+ioout:
+	ldi	r16, 0xfc	; PD7:2
+	out	DDRD, r16
+	ldi	r16, 0x3f	; PB5:0 (CP, WE, OE and CE too)
+	out	DDRB, r16
+	ret
+
+; Set PD7:2 and PB1:0 to input
+ioin:
+	ldi	r16, 0x03	; PD7:2
+	out	DDRD, r16
+	ldi	r16, 0x3c	; PB1:0
+	out	DDRB, r16
+	ret
+
+main:
+	ldi	r16, low(RAMEND)
+	out	SPL, r16
+	ldi	r16, high(RAMEND)
+	out	SPH, r16
+
+	; We begin with WE and OE disabled (high), but CE stays enabled (low)
+	; the whole time.
+	sbi	PORTB, FLWE
+	sbi	PORTB, FLOE
+	sbi	PORTB, FLCE
+
+	; Clear counters and flags
+	clr	r21
+	clr	r22
+
+	; Setup UART
+	ldi	R16, low(BAUD_PRESCALE)
+	sts	UBRR0L, r16
+	ldi	r16, high(BAUD_PRESCALE)
+	sts	UBRR0H, r16
+
+	ldi	r16, (1<<TXEN0)
+	sts	UCSR0B, r16
+
+loop:
+	rcall	ioout
+	rcall	nextaddr
+	rcall	ioin
+	rcall	readdata
+	rcall	uartwr
+	rjmp	loop
+
+