TM4C1290NCZAD: Using uDMA with I2C

Chris Lande

Part Number: TM4C1290NCZAD

Team,

I'm working from the app note SPMA073 using example 'ektm4c129_i2c_master_udma_fifo'. The demo is based on communicating with a 24C256 external memory device. The issue I have is I'm trying to communicate with a 24C02. The main difference is that the 24C256 use a 2 byte internal addressing scheme and the 24C02 uses a single byte internal addressing scheme.

Please will you detail the steps to change the 'ektm4c129_i2c_master_udma_fifo' example from using a 2 byte address internal address (24C256) to a single byte address (24C02)?

I have tried to do this myself but so far without success.

Thanks.

over 3 years ago

0 Ralph Jacobi over 3 years ago

TI__Guru*** 128125 points

Hello Chris,

I don't have a lot of familiarity with that example, but looking over it and what you described, then I would expect that you don't need the I2C_OP_TXADDR state anymore and could remove that.

To do so, you'd want to go right into I2C_OP_FIFO like this, and then use the 8 bit addressing:

	case I2C_OP_IDLE:
		//
		// Move from IDLE to Transmit Address State
		//
		g_ui8MasterPrevState = g_ui8MasterCurrState;
		g_ui8MasterCurrState = I2C_OP_FIFO;

		//
		// Write the upper bits of the page to the Slave
		//
		I2CMasterSlaveAddrSet(I2C2_BASE, SLAVE_ADDRESS_EXT, false);
		I2CMasterDataPut(I2C2_BASE, DataForSlaveAddressHere));
		I2CMasterControl(I2C2_BASE, I2C_MASTER_CMD_BURST_SEND_START);
		break;

That would be replacing all of this:

	case I2C_OP_IDLE:
		//
		// Move from IDLE to Transmit Address State
		//
		g_ui8MasterPrevState = g_ui8MasterCurrState;
		g_ui8MasterCurrState = I2C_OP_TXADDR;

		//
		// Write the upper bits of the page to the Slave
		//
		I2CMasterSlaveAddrSet(I2C2_BASE, SLAVE_ADDRESS_EXT, false);
		I2CMasterDataPut(I2C2_BASE, (g_ui16SlaveWordAddress >> 8));
		I2CMasterControl(I2C2_BASE, I2C_MASTER_CMD_BURST_SEND_START);
		break;

	case I2C_OP_TXADDR:
		//
		// Assign the current state to the previous state
		//
		g_ui8MasterPrevState = g_ui8MasterCurrState;

		//
		// If Address has been NAK'ed then go to stop state
		// else go the FIFO Priming State
		//
		if(ui32I2CMasterInterruptStatus & I2C_MASTER_INT_NACK)
		{
			g_ui8MasterCurrState = I2C_OP_STOP;
		}
		else
		{
			g_ui8MasterCurrState = I2C_OP_FIFO;
		}

		//
		// Write the lower bits of the page to the Slave if
		// Address has been ACK-ed
		//
		I2CMasterDataPut(I2C2_BASE, (g_ui16SlaveWordAddress >> 0));
		I2CMasterControl(I2C2_BASE, I2C_MASTER_CMD_BURST_SEND_CONT);
		break;

You may also need to remove I2C_OP_TXADDR from the I2C_MASTER_STATE.

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TM4C1290NCZAD: Using uDMA with I2C