KBA: How to do current measurements on WF(M)200 with the BRD8022A or the BRD8023A?
03/78/2019 | 10:47 AM
The BRD8022A provides a way to do current measurement (the same way is possible with the BRD8023A for WFM200).
The snapshot below provides the top overview of the BRD8022A board where U1 is the WF200:
In the blue circle, there is a way to do current measurement of the WF200. The schematic of this part is described below :
The R616 is a 0.1 Ohm resistor which connects the VMCU with the VMCU_NCP (WF200).
The J1 could be used to solder a HE10 connector (2.54mm) useful to do measurements.
So using R616 and J1, there are two ways to do WF200 current measurements during Tx, Rx or averaged on DTIM3:
using a Voltmeter on J1-1 and J2-2, you could monitor the R616 voltage and then compute the current consumption.
using a Ampere meter in serial between J1-1 and J1-2 after removing the R616 resistor.
Removing the R616 resistor, you could alternatively use a monitored power supply using J1, like described in the snapshot below:
We recommend this way, if you want to measure the average lowest current consumption of 22uA during the sleep state.
Moreover, to get the average sleep current consumption of 22uA, you should :
use the SPI interface because with the Raspberry Pi, the SDIO clock is not switched off during the sleep state (this increases the current consumption).
remove the SDIO/SPI pull-up resistors highlighted in yellow in the above top view (these pull-up are not needed with the Raspberry Pi because the host has internal pull-up on the interface like required by the standard).
In order to do WF200 current measurements in Tx, Rx or in sleep state, we have used the Keysight DC power analyzer N6705C set in 2-wire sensing for short supply cables (voltage is monitored at supply output terminals) else set in in 4-wire sensing for longer twisted supply cables (voltage is monitored at the load and automatically compensate for any voltage drop within supply cables).
KBA: How to do current measurements on WF(M)200 with the BRD8022A or the BRD8023A?
The BRD8022A provides a way to do current measurement (the same way is possible with the BRD8023A for WFM200).
The snapshot below provides the top overview of the BRD8022A board where U1 is the WF200:
In the blue circle, there is a way to do current measurement of the WF200. The schematic of this part is described below :
The R616 is a 0.1 Ohm resistor which connects the VMCU with the VMCU_NCP (WF200).
The J1 could be used to solder a HE10 connector (2.54mm) useful to do measurements.
So using R616 and J1, there are two ways to do WF200 current measurements during Tx, Rx or averaged on DTIM3:
Removing the R616 resistor, you could alternatively use a monitored power supply using J1, like described in the snapshot below:
We recommend this way, if you want to measure the average lowest current consumption of 22uA during the sleep state.
To better understand the current consumption provided in the WF200 datasheet, I recommend to read the following KBA : https://www.silabs.com/community/wireless/wi-fi/knowledge-base.entry.html/2019/03/05/kba_wfx200_dtim3-tmpo
Moreover, to get the average sleep current consumption of 22uA, you should :
In order to do WF200 current measurements in Tx, Rx or in sleep state, we have used the Keysight DC power analyzer N6705C set in 2-wire sensing for short supply cables (voltage is monitored at supply output terminals) else set in in 4-wire sensing for longer twisted supply cables (voltage is monitored at the load and automatically compensate for any voltage drop within supply cables).
For more details you could read this Application Note : https://www.silabs.com/documents/public/application-notes/an1219-power-consumption-wfm200.pdf