User Guide

PAMS
System Module DB6
NHB–3
Technical Documentation
Original 26/97
Page 4–34
Interface to the MCU is done with 8 bit data bus ,5 bit lower address bus, 4 bit
upper address bus, RSTRBEX, WSTROBEX, IRQX and NMI. ASIC is in the
same memory space as MCU memories. The ASIC generates chip selects
from the address bits A16–19. There is also M2BUS detector and netfree
counter on the ASIC. Netfree interrupt IRQX occurs if no activity is detected in
M2BUS in about 3ms. NMI is used to wake up the MCU from sleep mode.
MCU and DSP communicate through ASIC. ASIC has an MCU mailbox and a
DSP mailbox. MCU writes data to DSP mailbox where DSP can only read the
incoming data. In MCU mailbox the data transfer direction is the opposite. The
size of the mailbox is 64 * 8 bit.
MCU and User Interface (keyboard and display) communication is controlled
through the ASIC.
COL(0–3) are used as column lines in keyboard. UIF(0–5) are used as row
lines They are also multiplexed with display driver control signals.
When a key is pressed the ASIC gets a reset from row and starts scanning.
One column at the time is written to low and rows are used to read which key it
was.
Row lines and UIF6 are used for display driver control. UIF(0–3) are used as 4
bit parallel data bus for the LCD driver. UIF4 is used as read/write strobe, UIF5
to select data or instruction register and UIF6 as enable strobe.
The UIM interface is the electrical interface between the smart card used in the
DCS1900 applications and the MCU via the ASIC. ASIC converts the serial
data received from the UIM to parallel data for MCU and converts parallel data
from MCU to serial mode for the card. The UIM interface also takes care of the
power up and down procedure to the card, frame and parity error checking.
The communication between card and ASIC is asyncronous and half duplex.
Four signals are used between the ASIC and the UIM card: UIMDATA,
UIMCLK,UIMRESET and VUIM. The clock frequency is 3.25 MHz. When there
is no data transfer between the UIM card and the HP the clock can be reduced
to 1.625 MHz. Some UIM cards also allows the clock to be stopped in that
mode. Supply voltage VUIM can be switched off by the ASIC. The supply volt-
age is 4.65 V. The carddetect input on the ASIC is connected to BTYPE pin and
when the battery is removed the ASIC will drive the UIM down.
The interface to the DSP is done using 6 bit address bus, 16 bit data bus, IOX
and RWX lines. Data bus is latched using IOX, address bus is not. The ASIC
also generates interrupt INT0 when an edge occurs in DBUS line (if the mask
bit is off). INT1 is used as RX interrupt and as MFI modulator interrupt to the
DSP.
Viterbi is used to perform GSM/PCN convolutional decoding and bit detection
according to viterbi algorithm. It can be controlled and accessed throughly by
the DSP.
Coder is used to perform block encoding, decoding, and ciphering according to
GSM algorithm A5/1 or A5/2. (ASIC circuit supports both algorithms.)