mpc235 Megawin Technology, mpc235 Datasheet - Page 38

• Manufacturer Part Number: mpc235
• Description: Low-speed Usb Micro-controller
• Manufacturer: Megawin Technology

DPM control
DPM_CTL:
DPMO:
DPMI:
MPC235 provides a way to control D+ and D- pins by user’s firmware. The control focuses on PS/2
interface and in system program operations. The DPM.DPI and DPM.DMI record the D+ and D- pin
value respectively.
For PS/2 interface, firmware can judge the D+ and D- pins’ connection be USB or PS/2 protocol by
reading the value of DPI and DMI. The DPM_CTL.C1 and DPM_CTL.C0 set the controller of D+ and
D- pins. If they are set to 10, the D+ and D- pins are under CPU’s control, thus the USB function is
unavailable. DPM.DPO/DMO sets the value of D+/D- pin when CPU controls the D+/D- pin; Writing 0 to
DPO/DMO let the D+/D- pin to output low, writing 1 causes the pin to be pulled high (input mode). This
I/O control would be enough to perform PS/2 operation.
Programming Notice
The status after different reset condition is listed below:
*: some SFR are unchanged
38
Special Function Register
Address
00EAH
00E8H
00E9H
CPU Register
SRAM Data
C1, C0: D+/D- control selector.
DPO/DMO: D+/D- pin output (at {DPM_CTL.C1, DPM_CTL.C0}=10). 0: output low, 1: pull high (input)
DPI/DMI: D+/D- pin value (Read only)
DPM_CTL
DPMO
0x: controlled by USB Engine
10: controlled by CPU
Name
DPMI
Bit 7
-
-
-
Power on reset
Default value
Unknown
Unknown
MPC235 Technical Summary
Bit 6
-
-
-
Bit 5
-
-
-
CPU RESB pin reset
Default value (*)
Bit 4
Unchanged
-
-
-
Unknown
Bit 3
-
-
-
Bit 2
-
-
-
Default value (*)
Unchanged
WDT reset
Unknown
DPO
Bit 1
DPI
C1
MEGAWIN
DMO
Bit 0
DMI
C0
R
√
√
√
W
√
√
-