LMK04828BEVM: LMK04828BEVM

Hi Jeremy,

The LMK0482x supports both 3-wire and 4-wire SPI. When using your own SPI controller, you can use any of pins 5/31/48/58/59 for readback, in addition to the 3-wire mode supported over SDIO. But as you have observed, TICS Pro/USB2ANY can only use STATUS_LD2 pin for SPI readback. If you load the device defaults and try to read all registers, TICS Pro should prompt you if you would like to setup the device in readback mode. I'll flag an explanation of the readback requirements as something to include in the next revision of the user's guide.

You actually do not need to disable 3-wire SPI. You could run 3-wire SPI simultaneously with 4-wire SPI (usefulness notwithstanding). For 3-wire SPI, one other critical register is 0x0149[6] (SDIO_RDBK_TYPE) which sets the SDIO pin readback style as either open-drain or push-pull. If open-drain is selected (the POR default to prevent backdriving lower voltage controllers, 0x0149[6]=1), a pull-up resistor on the SDIO pin is required for readback to function. For push-pull, the SPI controller must be 3.3V-capable.

On the raw registers page:

• Read Register reads the register selected in the register map. Click on one of the registers or use the arrow keys to navigate in the register map, and the Read Register will link to that register.
• Read under the register/field name box can be used to read in any arbitrary register or field name by name (e.g. you can read "R2" instead of "0x0002", or you can read individual fields such as "SDIO_RDBK_TYPE"). Read has no dependence on the currently selected register in the register map.

Regards,

Hello Jeremy,

The minimum number of register writes required is typically only one, since the TYPE and MUX components are stored in the same register. For example, if you wanted to get 4-wire SPI working using CLKin_SEL1 as the readback pin, you would only need to write 0x0149 0x73 (0x0149[7:6] are not relevant to establishing 4-wire SPI). All registers should be available for read after configuring one of the pins for SPI MISO with this single register write.

There is only one exception: if the SPI_LOCK registers are set other than 0x1FFD00, 0x1FFE00, 0x1FFF53, the LMK04828 SPI will be disabled. In this case, the minimum required writes is four: the first three set 0x1FFd00, 0x1FFe00, 0x1FFF53 to unlock SPI, the fourth configures one of the GPIO as the SPI MISO pin.

Regards,