TMP1826: FLEXADDRESS command not working.

Paul Suess

Part Number: TMP1826

Hello everyone,

i am currently writing a driver for the TMP1826. We want to use the flexible address to asign each TMP sensor a fixed address.
I am currently able to read the Temperatur of a single sensor(with the skip address command), read and write the Scratchpad-1 and set the address programmatically. But when i use FLEXADDRESS (0Fh) + address Byte instead of SKIPADDRESS i dont get any results on read.
I couldn´t find an example for the actual use of the FLEXADDRESS command in the TMP datasheet, so I was wondering what i am missing.

Hope you could guide me in the right direction, thanks.

6 months ago

0 Ren Schackmann 6 months ago

TI__Mastermind 38985 points

Hi Paul,

After you set the short address, does it read back as expected? Note that you must also set the appropriate FLEX_ADDR_MODE in Config 2, and that the state of the short address is only updated (in the case of HW modes) when there is a change to FLEX_ADDR_MODE bits.y

FLEXADDR 0x0F is described in the flow chart Figure 9-20 where it's noted that byte is transmitted least significant bit first.

ASCStudio has FLEXADDR support in the tmp1826.c sendAddr() function:

/*
 *  ======== TMP1826_sendAddr ========
 *  Transmit the address portion of a OneWire transaction. 
 */
void TMP1826_sendAddr(TMP1826_Handle sensor)
{
    uint8_t i;
    
    if (sensor->addrMode == TMP1826_SKIP_ADDR) {
        /* this addrMode should only be used for single-device bus */
        mcu_txOneWireByte(sensor->busId, TMP1826_SKIP_ADDR);
    } else if (sensor->addrMode == TMP1826_FLEX_ADDR) {
        mcu_txOneWireByte(sensor->busId, TMP1826_FLEX_ADDR);
        mcu_txOneWireByte(sensor->busId, sensor->shortAddr);
    } else if (sensor->addrMode == TMP1826_MATCH_ADDR) {
        mcu_txOneWireByte(sensor->busId, TMP1826_MATCH_ADDR);
        for (i = 0; i < 8; i++){
            mcu_txOneWireByte(sensor->busId, sensor->devAddr >> (i*8));
        }
    } else if (sensor->addrMode == TMP1826_OVD_SKIP_ADDR) {
        /* this addrMode should only be used for single-device bus */
        mcu_txOneWireByte(sensor->busId, TMP1826_OVD_SKIP_ADDR);
        mcu_OneWireSetOverdrive(true);
    } else if (sensor->addrMode == TMP1826_OVD_MATCH_ADDR) {
        mcu_txOneWireByte(sensor->busId, TMP1826_OVD_MATCH_ADDR);
        for (i = 0; i < 8; i++){
            mcu_txOneWireByte(sensor->busId, sensor->devAddr >> (i*8));
        }
        mcu_OneWireSetOverdrive(true);
    }
}

Similarly, the example code for TI MCU on the TMP1826 product page has a similar sendDeviceAddress function in its tmp182x_func_driver.c

//*****************************************************************************
//
// Helper Function: Sends device address as per the Address Mode
//
//*****************************************************************************
void sendDeviceAddress(uint8_t uidevNo)
{
    if(oneWireBus.AddrMode == 0)
    {
        mcu_txOneWireByte(SKIP_ADDR,oneWireBus.BusSpeed);
    }
    else if(oneWireBus.AddrMode == 1)
    {
        mcu_txOneWireByte(FLEX_ADDR,oneWireBus.BusSpeed);
        mcu_txOneWireByte(tmp182x[uidevNo].acc_short_addr,oneWireBus.BusSpeed);
    }
    else
    {
        mcu_txOneWireByte(MATCH_ADDR,oneWireBus.BusSpeed);
        mcu_txOneWireByte(tmp182x[uidevNo].devAddr[0],oneWireBus.BusSpeed);
        mcu_txOneWireByte(tmp182x[uidevNo].devAddr[1],oneWireBus.BusSpeed);
        mcu_txOneWireByte(tmp182x[uidevNo].devAddr[2],oneWireBus.BusSpeed);
        mcu_txOneWireByte(tmp182x[uidevNo].devAddr[3],oneWireBus.BusSpeed);
        mcu_txOneWireByte(tmp182x[uidevNo].devAddr[4],oneWireBus.BusSpeed);
        mcu_txOneWireByte(tmp182x[uidevNo].devAddr[5],oneWireBus.BusSpeed);
        mcu_txOneWireByte(tmp182x[uidevNo].devAddr[6],oneWireBus.BusSpeed);
        mcu_txOneWireByte(tmp182x[uidevNo].devAddr[7],oneWireBus.BusSpeed);
    }

}

thanks,

ren

0 Paul Suess 6 months ago in reply to Ren Schackmann

Prodigy 10 points

Thank you for your answer.
I managed to find a mistake in the configuration.

All solved now.

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TMP1826: FLEXADDRESS command not working.