EM6580SO14A EMMICRO [EM Microelectronic - MARIN SA], EM6580SO14A Datasheet - Page 22

• Manufacturer Part Number: EM6580SO14A
• Description: Ultra Low Power 8-pin Flash Microcontroller
• Manufacturer: EMMICRO [EM Microelectronic - MARIN SA]

7. Serial Port
The EM6580 contains a simple, half duplex three wire synchronous type serial interface., which can be used to
program or read an external EEPROM, ADC, ... etc. Its I/O are multiplexed on Port A.
For data reception, a shift-register converts the serial input data on the SIN(PA[0]) terminal to a parallel format,
which is subsequently read by the CPU in registers RegSDataL and RegSDataH for low and high nibble. To
transmit data, the CPU loads data into the shift register, which then serializes it on the SOUT(PA[2]) terminal.
It is possible for the shift register to simultaneously shift data out on the SOUT terminal and shift data in on the
SIN terminal. In Master mode, the shifting clock is supplied internally by the Prescaler : one of three prescaler
frequencies are available, Ck[16], Ck[15] or Ck[14]. In Slave mode, the shifting clock is supplied externally on
the SCLKIn(PA[1]) terminal. In either mode, it is possible to program : the shifting edge, shift MSB first or LSB
first and direct shift output. All these selection are done in register RegSCntl1 and RegSCntl2.
Figure 12. Serial Interface Architecture
The PA[3..0] terminal configuration is shown in Figure 10 and 12. When the Serial Interface is used then care
should be taken not to use inputs and outputs needed for Serial Interface for other peripherals !:
∗ PA[0] {SIN} must be dedicated to Serial input if needed and can not be used for IRQ, Software Variable
∗ PA[1] {SCLK} is an output for Master mode {SCLKOut} and an input for Slave mode {SCLKIn}. But different
∗ PA[2] {SOUT} must be dedicated to Serial Data Output if needed and can not be used for Analogue input, or
∗ PA[3] {CS/ Ready } if used for serial Interface status output. When used for Serial Interface it should not be
Note:
Before using the serial interface, the corresponding circuit terminals must be configured accordingly.
Copyright © 2006, EM Microelectronic-Marin SA
External Slave Clock Source
(SCLKin from SCLK PA[1]
jumps or Output. It can be still used for Wake-Up on Change
functions can be Switched On/Off with care as they are needed.
other Output.
used for IRQ, Software Variable jumps or Output. It can be still used for Wake-Up on Change.
Source (ck[16,15,14])
Internal Master Clock
R
Status Registers
Control
&
Mux
Mode
Serial Input Data
from SIN PA[0]
Clock
Enable
Status
Control Logic
Write Tx Read Tx
Shift Ck
Start
22
8-bit Shift Register
Direct
Shift
(8th Shift Clock)
Shift complete
ResetStart
MSB;LSB
First
Status
Serial Master Clock Output
SCLKout to SCLK PA[1]
Serial Output Data to
SOUT PA[2]
IRQSerial
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EM6580
Status to
CS/Ready PA[3]