MB87P2020 Datasheet, PDF (349/356 Pages) Fujitsu Component Limited. – Colour LCD/CRT/TV Controller

Hints and Restrictions
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The inserted NOP command is for de-coupling PutTxtBM from Software Reset. All data were processed
finally and closed. To bring the ULB command processor the software reset function is called afterwards.
GDC_CMD_SwRs() itself executes the SWRES and NOP commands to bring all command processing de-
vices to an initial state (see also section 2.9).
An insertion of GDC_CMD_NOP() before each command register write (introduced in C-API former ver-
sions) is not required. Only at dedicated points in the software at situations described above the work around
is required. Other commands and with background enabled the error can not occur. Application examples
encountered only marginal performance loss at transparent text output over background drawings. For bit-
map transfer the additional two commands are not important.
Table 2-14 gives an overview and a classification about the described problem.
Table 2-14: Pixel engine commands
Subject
Description
Classification
Effects without
workaround
Solution/Workaround
Concerned devices
Testcase
Description
Pixel Engine signals end of command execution without stop signal from
command controller. This causes possible malfunction of command con-
troller for the next command processed.
HW limitation
Commands PutTxtBM, PutTxtCP, PutBM and PutCP with background
disable (BGCOL_EN=0) or ignore colour enable (IGNORCOL_EN=1) can
cause command control malfunction. This may lead to an incorrect execu-
tion of following commands.
Send NoOp-SwReset command sequence after PutTxt[BM|CP] if config-
ured with BGCOL_EN=0 or after Put[BM|CP] with IGNORCOL_EN=1.
This description is valid for Lavender and Jasmine.
MB87J2120 (Lavender)
MB87P2020 (Jasmine)
MB87P2020-A (Jasmine redesign)
EMDC: SDC.6
Because of the splitting between command and data write functions within API the NoOp-SwReset com-
mand sequence can not be included selectively after affected commands. This can only be done in target
application or in a higher level API. The C-API can’t solve this problem by inserting a GDC_CMD_NOP()
and GDC_CMD_SwRs() before each command register write activity without performance loss. It is rec-
ommended to solve this problem only at dedicated points in the higher level software if special background
conditions are relevant only.
2.12 Pixel read back commands (GetPixel, XChPixel)
Internal data flow blocks if REQCNT+1 data words does not fit into output FIFO. Therefore the full output
FIFO size is not useable in some cases.
If an application wants to collect data in output FIFO in order to transfer a complete block at once without
checking FIFO load for every data word for instance via DMA it is possible that not all data appear in output
FIFO and the initialized limit is not reached. Even if the next command was sent after GetPixel or XCh-
Pixel which is normally suitable to flush input FIFO data flow blocking is not escaped.
Note that this behaviour does not occur if output FIFO is read with flag polling for every data word be-
cause the amount of words in output FIFO falls below the limit FIFOSIZE-REQCNT-1 at a certain time.
GetPA is not affected because it uses other registers than REQCNT for block size calculation.
Restrictions
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