![background image](http://html1.mh-extra.com/html/rabbit/2000/2000_designers-handbook_3112103009.webp)
Designer’s
Handbook
5
3.
How Dynamic C Cold-Boots the Target System
Dynamic
C assumes that target controller boards using the Rabbit CPU have no pre-
installed
firmware. It takes advantage of the Rabbit’s bootstrap (cold boot) mode that
allows
memory and I/O writes to take place over the programming port.
When
the programming cable connects a PC serial port to the user’s system the PC run-
ning
Dynamic C is connected to the Rabbit as shown in Table 1..
The
programming cable includes an RS-232 to CMOS signal level converter circuit. The
level
converter is powered from the +5 V or +3.3 V power supply voltage present on the
Rabbit
programming connector (see Figure 7 on page 31). Plugging the programming
cable
into the Rabbit programming connector results in pulling the Rabbit SMODE0,
SMODE1
(startup mode) lines high. This causes the Rabbit to enter the cold-boot mode
after
reset.
3.1
How the Cold Boot Mode Works In Detail
The
microprocessor starts executing a 12-byte program contained in an internal ROM.
The
program contains the following code.
; origin zero
00
ld l,n
; n=0c0h for serial port A
; n=020h for parallel (slave port)
02
ioi ld d,(hl)
; get address most sig byte
04
ioi ld e,(hl)
; get least sig byte
06
ioi ld a,(hl)
; get data (h is ignored)
08
ioi or nop
; if D(7)==1 ioi, else nop
09
ld (de),A
; store in memory or I/O
10
jr 0
; jump back to zero
; note wait states inserted at bytes 3, 5 and 7 waiting
; for serial port or parallel port ready
The
contents of the boot ROM vary depending on the settings of SMODE1, SMODE2 and
on
the contents of register D bit 7 which determines if the store is to be an I/O store or a
data
store. If the boot is terminated by storing 80h to I/O register 24h then when the boot
Table
1.
Programming
Port
Connections
PC
Serial
Port
Signal
Rabbit
Signal
DTR
(output)
/RESET
(input, reset system)
DSR
(input)
STATUS
(gen purpose output)
TX
(serial output)
RXA
(serial input, chan A)
RX
(serial input)
TXA
(serial output, chan A)
Содержание 2000
Страница 1: ...Rabbit 2000 Microprocessor Designers Handbook Revision C...
Страница 4: ...Rabbit 2000 Microprocessor...
Страница 6: ...2 Rabbit 2000 Microprocesssor...
Страница 12: ...8 Rabbit 2000 Microprocessor...
Страница 34: ...344 Dynamic C User s Manual...
Страница 36: ...34 Rabbit 2000 Microprocessor...
Страница 44: ...42 Rabbit 2000 Microprocessor...