20-668-0024 Rabbit Semiconductor, 20-668-0024 Datasheet - Page 176

• Manufacturer Part Number: 20-668-0024
• Description: IC CPU RABBIT4000 128-LQFP
• Manufacturer: Rabbit Semiconductor

Specifications of 20-668-0024

• Processor Type: Rabbit 4000 8-bit
• Speed: 60MHz
• Voltage: 2.5V, 2.7V, 3V, 3.3V
• Mounting Type: Surface Mount
• Package / Case: 128-LQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -
• Other names: 20-668-0022; 316-1078

18.3.3 Master/Slave Communication
1. The master writes data to the appropriate external I/O address on the data bus for the
2. If the master is writing multiple bytes, it should write to SPD0R last since that will
3. The slave responds to the interrupt, reading the data from the slave port data registers.
18.3.4 Slave/Master Communication
1. The slave writes data to the appropriate slave port data register. If it is writing multiple
2. The master receives an external interrupt from the /SLVATTN line, and reads the data
18.3.5 Handling Interrupts
The interrupt request on the slave is cleared by either the master or the slave accessing one
of the slave port registers. To clear the interrupt without affecting the register values, a
dummy write can be made to SPSR.
18.3.6 Example ISR
A sample interrupt handler is shown below.
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slave device and register desired. For example, in the setup described here, the master
would write to register SPD2R on the first slave by writing to the address 0xC002
(0xC000 for the I6 strobe, and 0x0002 for SPD2R on that slave).
trigger an interrupt on the slave device. If only one byte is being sent, it should be
written to SPD0R.
bytes, SPD0R should be written last, which enables the /SLVATTN line.
out of the slave port data registers via external I/O reads on the data bus.
slave_isr::
push af
; read the data sent by the master
ioi ld a, (SPD2R)
ld (to_slv_d2), a
ioi ld a, (SPD1R)
ld (to_slv_d1), a
ioi ld a, (SPD0R)
ld (to_slv_d0), a
; if a response is required, perform it here
ld a, (to_mas_d2)
ioi ld (SPD2R), a
ld a, (to_mas_d1)
ioi ld (SPD1R), a
ld a, (to_mas_d0)
ioi ld (SPD0R), a
; the interrupt request is cleared by any read/write of the registers
pop af
ipres
ret
; save used registers
; this write asserts /SLVATTN
; restore used registers
Rabbit 4000 Microprocessor User’s Manual