
S1S60000 Technical Manual
Rev.1.5
EPSON
11
2.3
Serial Interface
GPIO[15:8] becomes the serial interface pin when the serial interface is in the enabled status and when host
interface is set off.
The serial interface is enabled when the following two conditions are met:
GPALT register bit [15:8] = FFh
GENCR register bit [10:8] (SERCONF) = “000” or “010” or “011”
The host interface is disabled when the following two conditions are met:
HIFSEL[2:0] pin = “LLL”
HIFCR register bit [10:8] (HIFSEL) = “111”
When the serial interface mode is enabled, the operation mode changes depending on the status of the SERCO
NF pin and the GPIO10 pin (MODE pins) settings.
Normally the system remains in the hardware control mode
while the host interface is disabled.
Table 2-1 shows relations between settings and operation modes.
Table 2.1
Setting of Serial Interface Operation Modes
GPALT[15:8]
SERCONF[2:0]
MODE
Mode
Communication conditions
000
-
Hardware control mode
Fixed (*1)
High
Hardware control mode
Fixed (*1)
010
Low
Serial emulation mode
(Active Open)
Variable (*2)
High
Hardware control mode
Fixed (*1)
011
Low
Serial emulation mode
(Passive Open)
Variable (*2)
FFh
Other than
above
-
Reserved. Do not set any other value.
-
00h
-
Varies according to host interface
setting.
Disabled: Hardware control mode
Enabled: Used as GPIO[15:8]
Fixed (*1)
-
Other than
above
-
Disabled. Does not operate in either
mode.
-
*1: Start-Stop synchronous serial, 9600 baud, 8-bit data, 1 stop-bit, no parity, no flow control.
*2: Set in the SERMODE register
Note: After selecting each mode, do no access the serial interface for 100ms.
2.3.1.
Hardware Control Mode
When the “hardware control mode” mentioned in Table 2.1 is set, the serial interface operates with the hardware
control mode.
Use of this mode allows confirming and changing each hardware status (EEPROM, I2C, GPIO)
from the serial interface.
Use this mode to change the status of the EEPROM when the host CPU is not
connected, or when you need to confirm the status of GPIO from the serial interface.
When the hardware control mode is set, the communication conditions are fixed as follows.
Start-Stop synchronous serial, 9600 baud, 8-bit data, 1 stop bit, no parity, no flow control
For details on this mode, refer to Chapter 5.1.4.