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Fix the CheckESPTimeout and its constant, remove WaitRaster, add init empty Rx FIFO #9

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Fix the CheckESPTimeout and its constant, remove WaitRaster, add init empty Rx FIFO #9

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e9b4c8c
add fast UART Rx FIFO clean
janko-jj Jun 16, 2026
efb586e
Removing WaitRaster, adjusting the ESPTimout constant calculation
janko-jj Jun 16, 2026
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4 changes: 3 additions & 1 deletion src/constants.inc.asm
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Original file line number Diff line number Diff line change
Expand Up @@ -22,7 +22,9 @@ CPUSpeed equ $07
VARS EQU $5c4b ; addr of variables area
NEXT_ONE_r3 EQU $19b8 ; find next variable

ESPTimeout EQU 65535*4;65535 ; Use 10000 for 3.5MHz, but 28NHz needs to be 65535
ESPTimeoutInSeconds EQU 60 ; Seconds, use this one to adjust timeout
; ESPTimeoutI is an 64-bit const which fits CheckESPTimeout
ESPTimeoutI EQU 65535 + ((22*ESPTimeoutInSeconds/10)<<16) ; formula for 28MHz

BORDCR EQU 23624

Expand Down
24 changes: 3 additions & 21 deletions src/esp-timeout.asm
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@@ -1,9 +1,9 @@
InitESPTimeout:
MODULE InitESPTimeout
push hl
ld hl, ESPTimeout mod 65536 ; Timeout is a 32-bit value, so save the two LSBs first,
ld hl, ESPTimeoutI mod 65536 ; Timeout is a 32-bit value, so save the two LSBs first,
ld (CheckESPTimeout.Value), hl
ld hl, ESPTimeout / 65536 ; then the two MSBs.
ld hl, ESPTimeoutI / 65536 ; then the two MSBs.
ld (CheckESPTimeout.Value2), hl
pop hl
ret
Expand All @@ -18,7 +18,6 @@ Value EQU $+1
ld hl, SMC
dec hl
ld (Value), hl
call WaitRaster
ld a, h
or l
jr z, Rollover
Expand All @@ -36,26 +35,9 @@ Value2 EQU $+1
or l
jr z, Failure ; If we hit here, 32 bit value is $00000000
dec hl
call WaitRaster
ld (Value2), hl
ld hl, ESPTimeout mod 65536
ld hl, ESPTimeoutI mod 65536
ld (Value), hl
jr Success

// https://github.com/remy/next-http/issues/7
WaitRaster:
push bc
push af
.waitloop:
ld bc, $243b
ld a, $1f ; only really care about lsb
out (c), a
inc b
in a, (c)
cp 192
jr nz, .waitloop
pop af
pop bc
ret

ENDMODULE
11 changes: 9 additions & 2 deletions src/uart.asm
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Expand Up @@ -48,7 +48,15 @@ SMC_skip_baud_init
rla ; Now in Bit 0
or %10000000 ; Set MSB to req. write to upper 7 bits
out (c), a
ret
; stale data taken out from FIFO at max speed
.staleFIFOclean
ld bc, UART_GetStatus
in a, (c)
rra
ret nc
ld bc, UART_RxD
in a, (c)
jr .staleFIFOclean

.baudTable:
DEFW 243,248,256,260,269,278,286,234 ; 115K
Expand Down Expand Up @@ -106,7 +114,6 @@ write:
IFDEF TESTING
call debug
ENDIF

ld bc, UART_GetStatus
.wait
in a, (c)
Expand Down