User Guide

NPE-4
2 - Broadband System PAMS Technical Documentation
Page 2-32 ãNokia Corporation. Original
Burst mode.
The flash device supports burst-mode. The purpose is to improve the date rate between
the flash and the UPP. The burst-mode can only be used for read operations. It is possible
to access the memory in burst-mode over the entire memory except for the 8 x 8 Kbytes
sectors. When using burst-mode at least 4 word (4*16 bits) is read from the flash. A read
operation from the flash, normally first set-up the address, and then the UPP will get the
data from this particular address. The address has to be set-up or sent to the flash ever
time the UPP wants to read from the flash. By using burst-mode the address only needs
to be sent one time, then flash will keep sending data as long as there is a clock-signal.
Flash programming.
The actual programming is indicated to the UPP by using the MBUS_RX signal between
the UPP and the UEM. The MBUS signal from the UEM to the flash prommer (FPS8 box) is
used as clock for the synchronous communication. The flash prommer keeps the MBUS
line low during UPP boot, to indicate that the flash prommer is connected. If the UPP
MBUS_RX signal is low on UPP, the MCU enters flash programming mode. If the signal is
high, the MCU starts loading software from the flash.
In order to avoid accidental entry to the "flash programming mode" the MCU only waits
for a specified time, to get input data from the flash prommer. If the timer expires with-
out any data being received, the MCU will continue the boot sequence. The MBUS signal
from UEM to the external connection is used as clock during flash programming. This
means that flash programming clock is supplied to the UPP on the MBUS_RX signal. The
flash prommer indicates to the UEM that flash programming/reprogramming by writing
an 8 bit password to the UEM. The data is transmitted on the FBUS_RX line and the UEM
clocks the data on the FBUS_RX line into a shift register. When the 8-bits have been
shifted in the register, the FPS8-box generates a falling-edge on the BSI line. This loads
the shift register content in the UEM into a compare register. These 8-bits will be com-
pared in a register to see if they match the "secret" default value inside the UEM. At this
point the flash prommer must pull the MBUS signal to UEM low, in order to indicate to
the MCU that the flash prommer is connected. The UEM reset-state machine performs a
reset to the system (PURX low for 10–100 ms). The UEM "flash programming mode" is
Figure 20 Burst-mode reading from the flash. Note that the address only is sent ones.
The flash keeps sending data to the UPP as long as the CS-signal and CLK are valid.