PCM18XK1 Microchip Technology, PCM18XK1 Datasheet - Page 196

• Manufacturer Part Number: PCM18XK1
• Description: MODULE PROC PIC18F8680,6680,8565
• Manufacturer: Microchip Technology

Specifications of PCM18XK1

• Accessory Type: Processor Module
• Lead Free Status / RoHS Status: Not applicable / Not applicable
• For Use With/related Products: ICE2000
• For Use With: ICE2000 - EMULATOR MPLAB-ICE 2000 POD
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

PIC18F6585/8585/6680/8680
17.3.5
The master can initiate the data transfer at any time
because it controls the SCK. The master determines
when the slave (Processor 2, Figure 17-2) is to
broadcast data by the software protocol.
In Master mode, the data is transmitted/received as
soon as the SSPBUF register is written to. If the SPI is
only going to receive, the SDO output could be dis-
abled (programmed as an input). The SSPSR register
will continue to shift in the signal present on the SDI pin
at the programmed clock rate. As each byte is
received, it will be loaded into the SSPBUF register as
if a normal received byte (interrupts and status bits
appropriately set). This could be useful in receiver
applications as a “Line Activity Monitor” mode.
The clock polarity is selected by appropriately program-
ming the CKP bit (SSPCON1<4>). This then, would
give waveforms for SPI communication, as shown in
FIGURE 17-3:
DS30491C-page 194
Write to
SSPBUF
SCK
(CKP = 0
CKE = 0)
SCK
(CKP = 1
CKE = 0)
SCK
(CKP = 0
CKE = 1)
SCK
(CKP = 1
CKE = 1)
SDO
(CKE = 0)
SDO
(CKE = 1)
SDI
(SMP = 0)
Input
Sample
(SMP = 0)
SDI
(SMP = 1)
Input
Sample
(SMP = 1)
SSPIF
SSPSR to
SSPBUF
MASTER MODE
SPI MODE WAVEFORM (MASTER MODE)
bit 7
bit 7
bit 7
bit 7
bit 6
bit 6
bit 5
bit 5
bit 4
bit 4
Figure 17-3, Figure 17-5 and Figure 17-6, where the
MSB is transmitted first. In Master mode, the SPI clock
rate (bit rate) is user programmable to be one of the
following:
• F
• F
• F
• Timer2 output/2
This allows a maximum data rate (at 40 MHz) of
10.00 Mbps.
Figure 17-3 shows the waveforms for Master mode.
When the CKE bit is set, the SDO data is valid before
there is a clock edge on SCK. The change of the input
sample is shown based on the state of the SMP bit. The
time when the SSPBUF is loaded with the received
data is shown.
bit 3
bit 3
OSC
OSC
OSC
/4 (or T
/16 (or 4 • T
/64 (or 16 • T
bit 2
bit 2
CY
)
bit 1
bit 1
CY
CY
)
)
 2004 Microchip Technology Inc.
bit 0
bit 0
bit 0
bit 0
Next Q4 Cycle
after Q2
4 Clock
Modes