Problem ARM912: DMA and ADC sems not working

dhoyen · ‎2008-09-15

Posted on September 16, 2008 at 08:57

dhoyen · ‎2011-05-17

Posted on May 17, 2011 at 09:55

Hi all,

I try to connect my ADC with a DMA access to push in memory, the result of a unique channel, but for an important number of sample .

Problem:

When i read the register DDR, in my ADC interrupt

the registre DDR (ADC->DDR) is always 0.

This register should receive something else...

Especially because my channel 5 receive something like 1.5-2v.

I can read 0x212 with the ADC->DR5 register, which is absolutely normal

I have activated the ADC_DMA mode : via ADC_DMACmd(ENABLE);

Is somebody have already experienced this problem ?

Could be a silicium limitation?

If somebody have already realized this operation, what is the value for the field :

DMA_InitStruct.DMA_Channel_FlowCntrl

DMA_InitStruct.DMA_Channel_Des

DMA_InitStruct.DMA_Channel_Src

(i don't know really between DMA_FlowCntrl_Perip2 or DMA_FlowCntrl2_DMA, and i have some trouble with the documentation)

thanks in advance.

Damien.

For the test, I m running my ADC in continuous mode,

Clock Peripheral, before prescaler : 48 Mhz (Look Init code)

My demo board is with a STR912FW44X6, silicon B (little bit old, but mounted by default). Compil: GCC / Yagarto

---- Init

ADC_Setup.ADC_Channel_5_Mode = ADC_NoThreshold_Conversion;

ADC_Setup.ADC_Select_Channel = ADC_Channel_5;

ADC_Setup.ADC_Scan_Mode = DISABLE;

ADC_Setup.ADC_Conversion_Mode = ADC_Continuous_Mode;

ADC_PrescalerConfig(128);

/* Enable DMA for ADC*/

ADC_DMACmd(ENABLE);

---- Interrupt -----

static u16 DMAData;

static u16 ConvertResult;

if (ADC_GetFlagStatus (ADC_FLAG_ECV) == SET )

{

ADC_ClearFlag (ADC_FLAG_ECV);

DMAData = ADC->DDR; // <- Receive always 0

ConvertResult = ADC->DR5; // <- Receive 0x212

}

rgreenthal · ‎2011-05-17

Posted on May 17, 2011 at 09:55

Need to setup Linked Lists for the received data buffer, like this for SSP

(change SSP0_BASE+2 to your input, i.e. ADC->DR5 (ADC_BASE+offset))

// Receive Control Link List

StructLinkList LLRxBuffer = {

(long*)SSP0_BASE+2, // source pointer

(long*)&usNetRxBuffer[0], // destination

(long*)&LLRxBuffer, // rotating buffer

// Channel Control

(long) DMA_DesIncrement // destination increment, NewFWLib name

| DMA_SrcWidth_HalfWord // source 16 bits

| DMA_DesWidth_HalfWord // destination 16 bits

| RX_BUFFER_SIZE, // length

// Channel Configuration

(long) DMA_FlowCntrl2_DMA // flow control

| DMA_SRC_SSP0_RX // source SSP0 receive

};

Also need to load this by using

ExecLinkList(DMA_Channel0, &LLRxBuffer);

where

/***********************************

Configure Channel and Execute

ExecLinkList(DMA_Channel0, &LLFpRxBuffer);

ExecLinkList(DMA_Channel1, &LLFpTxCommand);

ExecLinkList(DMA_Channel2, &LLNetRxBuffer);

ExecLinkListLength(DMA_Channel3, &LLNetTxCommand, nLength);

************************************/

void ExecLinkList(DMA_Channel_TypeDef * Channel, StructLinkList * LinkList)

{

// Channel->CCNF &= ~DMA_ChannelEnable;

DMA_ChannelCmd(Channel, DISABLE);

Channel->SRC = (long)LinkList->p_lSource;

Channel->DES = (long)LinkList->p_lDest;

Channel->LLI = (long)LinkList->p_lNextList;

Channel->CC = (long)LinkList->lControl;

// CCNF not part of link list

Channel->CCNF = (long)LinkList->lConfig;

// Channel->CCNF |= DMA_ChannelEnable;

DMA_ChannelCmd(Channel, ENABLE);

} // End of Function ''ExecLinkList()''

dhoyen · ‎2011-05-17

Posted on May 17, 2011 at 09:55

Hi rgreenthal,

Thanks for your help.

I tried to change the ADC->DDR register to the adress of the ADC->DR5 Register. Problem is I don't know really how the ADC will be able to generate a DMA request transfert if this DDR register don't works.

I tried to generate myself in the interrupt ADC end of convertion

a DMA request, via these function :

DMA_SetSReq (DMA_External_Req1_Mask);

DMA_SetBReq (DMA_External_Req1_Mask);

But nothing, no data is written in my destination buffer, stay with init value.

Any idea welcome.

Damien

dhoyen · ‎2011-05-17

Posted on May 17, 2011 at 09:55

Well,

he seems the silicon version, present in my demo board

: STR912F W44X6 (not A)... is limited.

The ADC Timer trigger is only available for rev A.

Same code running on a STR911FA W44X6 (A) seems work (TBC)

regards