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Chapter 3.6 Interrupt by µDMA
There might be problems when using µDMA with UART or PPG.
1) Detailed of bug for uDMA transmission
Fujitsu found the bug, as uDMA transmission is not operated normally for
MB90480/485 series. The bug has two combinations as following.
1.uDMA and UART (Synchronization/Asynchronization) transmission
2.uDMA and PPG
Also we have already checked the combination between uDMA and other resource.
But there was no bug for other combination.
Resource Result
External interrupt
{
PWC0
{
PPG0/1
±
PPG2/3
±
PPG4/5
±
Input capture 0 load
{
Input capture 1 load
{
UART(Synchronization/Asynchronization)
receive completed
{
UART(Synchronization/Asynchronization)
transmit completed
±
Output compare 0 match
{
Output compare 1 match
{
Output compare 2 match
{
Free-run timer / Reload timer
{
SIO1
{
SIO2
{
A/D
{
Table 1. Check list of combination between uDMA and other resource
1-1) Detailed of bug with combination between uDMA and UART
(Synchronization/Asynchronization) transmission
When the serial data is sent continuously from UART
(Synchronization/Asynchronization) with using uDMA, Fujitsu found that less
bytes than set bytes is outputted for FLASH device. The root cause of this
behavior is to operate continuously next uDMA transmission, because interrupt
clear timing of UART (Synchronization/Asynchronization) transmission is
delayed. However for Evaluation device, when [debug mode] is used, expected
data is outputted because internal operating is low speed. And when [native
mode] is used, the behavior of bug is occurred for FLASH and MASK device. And
at using only UART (Synchronization/Asynchronization) (not using uDMA), this
bug is not occurred.
1-2) Detailed of bug with combination between uDMA and PPG
When the output of PPG is changed continuously with using uDMA, Fujitsu found
that expected waveform is not outputted. This behavior is the root cause of
specification as interrupt source of PPG is not cleared by uDMA. However at
using only PPG (not using uDMA), this bug is not occurred.