Raspberry Pi spidev.h SPI Communication - c

I try to establish a spi communication from RPi (Master) to an EtherCAT Device (Slave).
The transfer of data got a scheme.
I have to transfer 2 bytes which address registers and the following bytes transfer data till a chip select terminates the communication.
This is my created attempt. With cs_change, i can tell my spi communication to deselect Chip Select before the next transfer starts.
char transfer(UINT8 data, char last)
{
char last_transfer = last;
int ret;
uint8_t tx[] = { data };
uint8_t rx[ARRAY_SIZE(tx)] = { };
struct spi_ioc_transfer tr = {
.tx_buf = (unsigned long)tx,
.rx_buf = (unsigned long)rx,
.len = ARRAY_SIZE(tx),
.delay_usecs = delay,
.speed_hz = speed,
.bits_per_word = bits,
.cs_change = 0,
};
if (last_transfer)
tr.cs_change = 1;
ret = ioctl(fd, SPI_IOC_MESSAGE(1), &tr);
if (ret < 1)
printf("can't send spi message");
return rx[tr.len-1];
}
First problem:
I think it is too late to deselect Chip Select first at new transfer.
So my first question: Is there another way to control my Chip Select signal, maybe another library i can use?!
Second problem:
I want to read from spi without writing on it, how can i realise that ( with a simple read(fd...) ?!)
I hope you guys can support me :)

Now this is spidev_test.c application you are referring to. The implementation seems to work as slave SPI device would be deselected after your last transfer. It stays selected until after the last transfer in a message.
Each SPI device is deselected when it's not in active use, allowing other drivers to talk to other devices as may be your SPI bus is shared among other slave SPI devices.
And moreover you are going for full-duplex.
Standard read() operation is obviously only half-duplex.
So whenever your SPI slave device wants to send data to the SPI controller(Master), then it must have some interrupt mechanism so that your driver/app can set the SPI controller to "SPI_IOC_RD_MODE" and can make "SPI_IOC_MESSAGE" providing only rx_buf OR you can go for only simple read() operation as the transfer would be half_duplex after setting the SPI controller to read mode. -Sumeet

You can use SPI_NO_CS mode and toggle the CS pins as GPIO using the wiringPi library... (from http://wiringpi.com/ )

Related

Mixed voltage reading from different AD7606 channels

Please help! I am using FSMC to connect a STM32F407 MCU with AD7606 to sample voltage value. MCU would send sampled values to PC using USB HS port after 1024 conversions. But when I inspect the values from PC, I found that readings from channel 0 occasionally contains data from other channels. For example, if connect channel 0 to 5v, connect channel 8 to 3.3v, connect other channels to ground. Then the printed value from channel 0 would contain 5v, 0v, 3.3v. The basic setup is as follows:
A 200KHZ PWM single is generated by TIM10 to act as CONVST signal for AD7606.
7606 will then issue a BUSY signal which I used as an external interrupt source.
In the Interrupt handler, An DMA request would be issued to read 8 16bit data
from FSMC address space to memory space. TIM10 PWM would be stopped if 1024
conversions has been done.
In the DMA XFER_CPLT call back, if 1024 conversions has been done, the converted
data would be sent out by USB HS port, and TIM10 PWM would be enabled again.
Some code blocks:
void HAL_GPIO_EXTI_Callback(uint16_t GPIO_Pin)
{
if(GPIO_Pin == GPIO_PIN_7)
{
// DMA data from FSMC to memory
HAL_DMA_Start_IT(&hdma_memtomem_dma2_stream0, 0x6C000000, (uint32_t)(adc_data + adc_data_idx) , 8);
adc_data_idx += 8;
if (adc_data_idx >= ADC_DATA_SIZE)
HAL_TIM_PWM_Stop(&htim10, TIM_CHANNEL_1);
}
}
void dma_done(DMA_HandleTypeDef *_hdma)
{
int i;
int ret;
// adc_data[adc_data_idx] would always contain data from
// channel 1, led1 wouldn't light if every thing is fine.
if (adc_data[adc_data_idx] < 0x7f00 )
HAL_GPIO_WritePin(led1_GPIO_Port, led1_Pin, GPIO_PIN_SET);
if (adc_data_idx >= ADC_DATA_SIZE)
{
if(hUsbDeviceHS.dev_state == USBD_STATE_CONFIGURED)
{
// if I don't call CDC_Transmit_HS, everything is fine.
ret = CDC_Transmit_HS((uint8_t *)(adc_data), ADC_DATA_SIZE * 2 );
if (ret != USBD_OK)
{
HAL_GPIO_WritePin(led1_GPIO_Port, led2_Pin, GPIO_PIN_SET);
}
}
adc_data_idx = 0;
HAL_TIM_PWM_Start(&htim10, TIM_CHANNEL_1);
}
}
It seems that a single USB transaction would take longer than 5us(one conversion time), so I stopped PWM signal to stop conversion...
If I only send the second half of the data buffer, there is no data mixture. It's very strange.
According to your description, I think the processing is correct, and the problem is at the CDC_Transmit_HS(); I have met the problem on the CDC_Transmit_FS(), which can't transmit more than 64 bytes data for original code, and need to modify some code, otherwise the some error occurs. Did you check the number of received data is correct?
Reference:
I can't receive more than 64 bytes on custom USB CDC class based STM32 device
I'm not sure your ADC_DATA_SIZE size; if it's larger than 64 bytes, maybe you can modify to smaller than 64 bytes and try again and check whether or not the data is correct. I am not sure if it is affected by this problem, but I think you can give it a try.
On the other hand, it may also be necessary to GND the ADC IN pins not used by AD7606 to avoid interference between channels.
Or you can try other communication (I2C, SPI, UART...etc) to send the data.
If there is no problem with other communication methods, there is a high chance that it is a problem with CDC_Transmit_HS(). If there are problems with other transmission methods, you may have to check whether there is a conflict between the ADC conversion time or the transmission time.

Why there is a word address in this I2C example code from FTDI?

I have been working on FTDI FT2232H chip to interface with I2C devices. I have started to learn AN_177 application note pdf. I have no EEPROM to expreience,no oscilloscope to see waveforms. My goal is to comprehend the code itself and taking notes for my future projects. Here is the code snippet that i dont completely understand:
FT_STATUS write_byte(uint8 slaveAddress, uint8 registerAddress, uint8 data)
{
uint32 bytesToTransfer = 0;
uint32 bytesTransfered;
bool writeComplete=0;
uint32 retry=0;
bytesToTransfer=0;
bytesTransfered=0;
buffer[bytesToTransfer++]=registerAddress; /* Byte addressed inside EEPROM */
buffer[bytesToTransfer++]=data;
status = I2C_DeviceWrite(ftHandle, slaveAddress, bytesToTransfer, buffer, &bytesTransfered, I2C_TRANSFER_OPTIONS_START_BIT|I2C_TRANSFER_OPTIONS_STOP_BIT);
/* poll to check completition */
while((writeComplete==0)&& (retry<I2C_WRITE_COMPLETION_RETRY))
{
bytesToTransfer=0;
bytesTransfered=0;
buffer[bytesToTransfer++]=registerAddress; /* Addressed inside EEPROM */
status = I2C_DeviceWrite(ftHandle, slaveAddress, bytesToTransfer,buffer, &bytesTransfered, I2C_TRANSFER_OPTIONS_START_BIT|I2C_TRANSFER_OPTIONS_BREAK_ON_NACK);
if((FT_OK == status) && (bytesToTransfer == bytesTransfered))
{
writeComplete=1;
printf(" ... Write done\n");
}
retry++;
}
return status;
}
You can see and understand that the while loop is the polling part.
I checked the datasheet of 24LC024H I2C EEPROM and they mentioned about Acknowladge Polling (Page 10) is a feature of this kind of EEPROMs'. Acknowladge Polling basicly checks when the device is ready to send data. There is a flow diagram too... you could take a look.
Flowchart
Here comes the what i want to point out:
buffer[bytesToTransfer++]=registerAddress; /* Addressed inside EEPROM */
In the 24LC024H datasheet related to Acknowladge Polling they say polling part consist of START + Control Byte (or Slave address) + R/W bit, not include address inside EEPROM (Word address in I2C protocol) . So why FTDI guys included this line of code? Am I missing something?
Best regards...

pic32 only receives 1 byte in spi

I'm struggling with, probably, a very simple problem.
I have a Cypress CY8 controller acting as SPI master, which should communicate with a PIC32mx in slave mode to exchange data packets.
However i cannot even fix simple transmission of multiple bytes from the master to the slave. I've set up the cypress to transmit a char of increasing value (0-255) with a pause (and slave select toggle) in between. The pic should read the incoming byte and then print it over uart to my pc (the uart connection works).
But the pic only prints the first character it receives continuously instead of it being updated.
If i check my logic sniffer, the cypress does send incrementing values and the pic relays them back over the MISO line (looks like the shift buffer isn't cleared).
What could this be?
The cypress without the pic attached gives proper output:
https://dl.dropboxusercontent.com/u/3264324/Schermafdruk%202015-07-28%2015.43.28.png
With the pic attached it relays the data over MISO:
https://dl.dropboxusercontent.com/u/3264324/Schermafdruk%202015-07-28%2015.43.45.png
And this is my (now) extremely basic code to test it:
TRISBbits.TRISB2 = 1; // make Ra2 pin input (SDI)
TRISBbits.TRISB5 = 0; // make Ra2 pin output (SDO)
TRISBbits.TRISB15 = 1; //make RB14 output (SCK)
ANSELA = 0; // all ports digital
ANSELB = 0; // all ports digital
SYSKEY = 0x00000000;
SYSKEY = 0xAA996655;
SYSKEY = 0x556699AA;
CFGCONbits.IOLOCK=0; // unlock configuration
CFGCONbits.PMDLOCK=0;
SDI2R = 0b0100; //SDI2 on pin RB2
SS2R = 0b0011; //SS2 on pin rb10
RPB5R = 0b0100; //SDO2 on pin RB5
// SCLK is connected to pin RB14 (SCK) by default
SYSKEY = 0x00000000;
SPI2CON = 0; // Stops and resets the SPI1.
rData=SPI2BUF; // clears the receive buffer
SPI2BRG=207; // use FPB/4 clock frequency <-- not important in slave mode right?
SPI2STATCLR=0x40; // clear the Overflo
SPI2CON=0x8180;
unsigned char t;
while(1){
t = SpiChnReadC(2);
//t = SPI2BUF; <== i've tried this also
sendData(t); <== uart routine
}
As i do receive a character and the spi data is relayed back to the cypress constantly i think something goed wrong with reading/clearing the spi data structure in the PIC. But i can't figure out why.
As i read in the datasheet, reading from SPI2BUFF gives me the received data, and clears the read flags so new data can be received, but it looks like that doesn't happen...
Can someone shine a light on this for me?
Thanks in advance
Timberleek
You should try making you SPI handler ISR driven to keep you from constantly polling, can also help the debugging since you'll only get notifications when the SPI is actually transacting.
NOTE: I'm bringing this from my FreeRTOS impl, so my ISR definition is not XC32 exactly...
/* Open SPI */
SPI1CON = 0;
spi_flags = SPICON_MODE32 | SPICON_ON;
SpiChnOpen(1,spi_flags,BRG_VAL);
SpiChnGetRov(1,TRUE);
mSPI1ClearAllIntFlags();
mSPI1SetIntPriority(priority + 1);
mSPI1SetIntSubPriority(0);
mSPI1RXIntEnable(1);
void vSPI1InterruptHandler(void)
{
unsigned long data;
if (IFS0bits.SPI1EIF == 1)
{
mSPI1EClearIntFlag();
}
if (IFS0bits.SPI1RXIF == 1)
{
data = SPI1BUF;
//sendData(data);
}
mSPI1RXClearIntFlag();
}

Using DMA to read EEPROM on SPI (SSP) Bus

I'm using an NXP LH79525, ARM7TDMI based processor. There is an EEPROM connected via SPI bus to the SSP port.
The objective is to read the EEPROM into SRAM for faster accessing.
The present working code sends a read command to the EEPROM, the reads the data byte per byte, which takes a long time.
I want to use the DMA to read EEPROM on the SPI bus directly, without intervention from the CPU.
Here is my code snippet:
// Initialize the DMA for use with SPI bus.
// Source is the EEPROM on the SPI bus.
// Destination is "buffer".
p_dma_stream_2->source_low = 0U;
p_dma_stream_2->source_high = 0U;
const uint32_t dest_addr = (uint32_t) buffer;
p_dma_stream_2->dest_low = (dest_addr & 0xFFFFU);
p_dma_stream_2->dest_high = (dest_addr >> 16U);
p_dma_stream_2->max_count = bytesToRead;
*p_dma_intr_mask = 0U; // Disable all dma interrupts.
*p_dma_intr_clear = 0xFF; // Clear the interrupts.
SSP->dmacr = 0x01; // Enable reading with DMA
p_dma_stream_2->control = 0x06U; // + 0x01 to enable transfer.
// 0x400 - status of stream 2. 1 == stream is active.
uint32_t status = *p_dma_status;
while ((status & 0x400U) != 0U)
{
OSTimeDelay(10U); // 10 milliseconds
status = *p_dma_status;
}
I'm reading incorrect values from the EEPROM when using the above example.
The DMA registers are counting correctly.
The SSP is already initialized before this code fragment, for reading bytes.
I'm looking for a working code example snippet, but haven't found any on the web.
According to this User's Guide table 5-1 it seems as SSPRX is assigned to Stream 0 and supports only half-word source data width (table 5-15).
Your code seems to use Stream 2 and byte adressing.

Receiving SPI data via DMA on PIC32

I know that this topic (DMA & SPI) has already been talked about on numerous threads in the microchip forum, actually i've read all the 15 pages in result of the search with keyword "dma" and read all the topics about dma & spi.
And I am still stuck with my problem I hope someone can help me :)
Here is the problem.
My chip is a PIC32MX775F512H.
I am trying to receive (only receive) data using SPI via DMA.
Since you cannot "just" receive in SPI, and that the SPI core starts toggling the SPI clock only if you write into the SPIBUF (SPI1ABUF for me) I am trying to receive my data using 2 DMA channels.
DMA_CHANNEL1 for the transmitting part.
DMA_CHANNEL2 for the receiving part.
I copy pasted the code from http://www.microchip.com/forums/tm.aspx?tree=true&high=&m=562453&mpage=1#
And tried to make it work without any luck. It only receives several bytes (5 or 6).
I've set the Event Enable Flags to DMA_EV_BLOCK_DONE for both dma channels, no interrupt occurs.
Do you have any idea ?
Here is the code I am using :
int Spi_recv_via_DMA(SPI_simple_master_class* SPI_Port, int8u *in_bytes, int16u num_bytes2)
{
DmaChannel dmaTxChn=DMA_CHANNEL1;
DmaChannel dmaRxChn=DMA_CHANNEL2;
SpiChannel spiTxChn=SPI_Port->channel;
int8u dummy_input;
DmaChnOpen(dmaTxChn, DMA_CHN_PRI3, DMA_OPEN_DEFAULT);
DmaChnOpen(dmaRxChn, DMA_CHN_PRI3, DMA_OPEN_DEFAULT);
DmaChnSetEventControl(dmaTxChn, DMA_EV_START_IRQ_EN | DMA_EV_START_IRQ(_SPI1A_RX_IRQ));
DmaChnSetEventControl(dmaRxChn, DMA_EV_START_IRQ_EN | DMA_EV_START_IRQ(_SPI1A_RX_IRQ));
DmaChnClrEvFlags(dmaTxChn, DMA_EV_ALL_EVNTS);
DmaChnClrEvFlags(dmaRxChn, DMA_EV_ALL_EVNTS);
DmaChnSetEvEnableFlags(dmaRxChn, DMA_EV_BLOCK_DONE);
DmaChnSetEvEnableFlags(dmaTxChn, DMA_EV_BLOCK_DONE);
//SpiChnClrTxIntFlag(spiTxChn);
//SpiChnClrRxIntFlag(spiTxChn);
DmaChnSetTxfer(dmaTxChn, tx_dummy_buffer, (void *)&SPI1ABUF, num_bytes2, 1, 1);
DmaChnSetTxfer(dmaRxChn, (void *)&SPI1ABUF, in_bytes, 1, num_bytes2, 1);
while ( (SPI1ASTAT & SPIRBE) == 0)
dummy_input = SPI1ABUF;
SPI1ASTAT &= ~SPIROV;
DmaRxIntFlag = 0;
DmaChnEnable(dmaRxChn);
DmaChnStartTxfer(dmaTxChn, DMA_WAIT_NOT, 0);
while(!DmaRxIntFlag);
return 1;
}
with those two interrupt handlers :
// handler for the DMA channel 1 interrupt
void __ISR(_DMA1_VECTOR, ipl5) DmaHandler1(void)
{
int evFlags; // event flags when getting the interrupt
//LED_On(LED_CFG);
INTClearFlag(INT_SOURCE_DMA(DMA_CHANNEL1)); // acknowledge the INT controller, we're servicing int
evFlags=DmaChnGetEvFlags(DMA_CHANNEL1); // get the event flags
if(evFlags&DMA_EV_BLOCK_DONE)
{ // just a sanity check. we enabled just the DMA_EV_BLOCK_DONE transfer done interrupt
DmaTxIntFlag = 1;
DmaChnClrEvFlags(DMA_CHANNEL1, DMA_EV_BLOCK_DONE);
}
// LED_Off(LED_CFG);
}
void __ISR(_DMA2_VECTOR, ipl5) DmaHandler2(void)
{
int evFlags; // event flags when getting the interrupt
INTClearFlag(INT_SOURCE_DMA(DMA_CHANNEL2)); // acknowledge the INT controller, we're servicing int
evFlags=DmaChnGetEvFlags(DMA_CHANNEL2); // get the event flags
if(evFlags&DMA_EV_BLOCK_DONE)
{ // just a sanity check. we enabled just the DMA_EV_BLOCK_DONE transfer done interrupt
DmaRxIntFlag = 1;
DmaChnClrEvFlags(DMA_CHANNEL2, DMA_EV_BLOCK_DONE);
}
}
So I end up waiting forever at the line : while(!DmaRxIntFlag);
I have put breakpoints in the interrupt vectors, they are never called.
This is the state of several registers during the ever lasting wait :
DMACON 0x0000C800
DMASTAT 0x00000001
I am using SPI1A port, so SPI1ABUF and _SPI1A_RX_IRQ
DCH1SPTR 0x5
DCH1SSIZ 0x2B
DCH2DPTR 0x6
DCH2DSIZ 0x2B
DCH2CON 0x00008083
DCH2ECON 0x1B10
DCH2INT 0x00800C4
DCH2SSA 0x1F805820
DCH2DSA 0x00000620
Channel 1 is used to transmit
Channel 2 is used to receive
You are missing these:
INTEnable(INT_SOURCE_DMA(dmaTxChn), INT_ENABLED); // Tx
INTEnable(INT_SOURCE_DMA(dmaRxChn), INT_ENABLED); // Rx
rigth before
DmaRxIntFlag = 0;
DmaChnEnable(dmaRxChn);
DmaChnStartTxfer(dmaTxChn, DMA_WAIT_NOT, 0);
Good luck!
Are you using the SPI in slave mode? or you are on master mode, trying to read some response for a command?
Have you check the silicon errata for this chip? The dspic 33fj family had an issue where SPI slave mode simply didn't work.
Other than that, I don't think it is a good idea to busy wait for DmaRxIntFlag change. You should configure the DMA transfer and continue with your main loop. The DMA will trigger the interrupt handler.
Hope this helps.

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