UVM e vr_ad -- Specman Read/Write Register Enhancements

If you are a Specman vr_ad user, you probably know that register access is implemented  using the read_reg / write_reg. For reading/writing a register, you have to

1. Extend a vr_ad_sequence

2. Add a field of the type of the register you want to access

3. In the body() , call the read/write_reg

For example:

extend MAIN vr_ad_sequence {

    !tx_data_reg : VR_AD_TX_DATA  vr_ad_reg;

    !tx_mode_reg : VR_AD_TX_MODE  vr_ad_reg;

    body() @driver.clock is only {

        read_reg {.driver == reg_driver} tx_data_reg;

        read_reg {.driver == reg_driver} tx_mode_reg;

    };

};

For simplifying test writing, starting Specman 12.1 the read/write_reg actions can:

• Be called from any TCM, not only from within a sequence
• Access not only a local field, but also a variable, or a reference to a field within the e registers model

One of the nice capabilities achieved with these enhancements is that you can embed access to registers among other activities. For example -- in a system level sequence, as in this code example :

extend SEND_AND_CHECK system_seq {

  !serial_frame : LEGAL frame;

  body() @driver.clock is {

    // Perform activity on serial interface, via the i/f driver

    do serial_frame on driver.serial_driver; 

    // Local variable of a register, read it and check the value

    var status_reg : STS vr_ad_reg;

    read_reg {.driver == driver.reg_driver} status_reg;

    check that status_reg.get_cur_value() == 0x37;

    // Access registers without defining fields nor variables

    write_reg {.driver == driver.reg_driver} driver.reg_model.reg0 val 0x12;

    write_reg {.driver == driver.reg_driver} driver.reg_model.reg1 val 0xFA;

    write_reg {.driver == driver.reg_driver} driver.reg_model.reg2 val 0x3;

    write_reg {.driver == driver.reg_driver} driver.reg_model.reg3 val 0x0;

    };

};

Note that register accesses are handled by the vr_ad_driver. So, when accessing a register from a TCM which is not a vr_ad sequence, you have to specify the vr_ad_driver to handle this operation.

We encourage you to check out the latest UVM e reference manual and user guide for details (both are part of Cadence Help).

Enjoy verification

Efrat Shneydor & Reuven Naveh,

UVM e