SLUSE48B May 2021 – November 2023 BQ79652-Q1 , BQ79654-Q1 , BQ79656-Q1
PRODUCTION DATA
Propagates:
The WAKE and SLEEPtoACTIVE pings/tones are part of the normal operation to wake up the device; hence, these two pings/tones can propagate to the next device in a daisy chain configuration. That is, when a device receives a WAKE ping/tone, it generates a WAKE tone and forwards it to the next device. Similar action applies to SLEEPtoACTIVE ping/tone.
The direction of the tone forwarding follows the communication direction, which is set by the CONTROL1[DIR_SEL] bit. See Section 9.3.6.1 for more details. The detection of the tone is supported from the COMH and COML ports on stack devices regardless of the [DIR_SEL] setting. This does not apply to base device because base device detects pings instead.
During normal operation, host can simply send a WAKE or SLEEPtoACTIVE ping to the base device and the corresponding tone will be generated to the rest of the stack devices. During system development, if there is a need to send WAKE or SLEEPtoACTIVE to only some of the devices in the daisy chain, host can use the CONTROL1[SEND_WAKE] or CONTROL1[SEND_SLPTOACT] bit. Device that receives this command will send the corresponding tone to the next device in the daisy chain. Because the WAKE and SLEEPtoACTIVE tones propagate, the rest of the daisy chain connected above also receives the corresponding tone.
Does Not Propagate:
The SHUTDOWN and HW_RESET pings/tones are mostly used as a communication recovery attempt. Hence these pings/tones do not propagate. That is, when a device receives a SHUTDOWN ping/tone, it starts the shutdown process but the device does not generate another SHUTDOWN tone to the next device. Similar action applies to HW_RESET ping/tone.
For a base device, as RX pin is connected to the host, SHUTDOWN or HW_RESET ping can be used on the base device. For stack devices, it is required at least one stack device is connected to the problem device is communicable. Host has to talk to the neighboring device and sets the CONTROL1[SEND_SHUTDOWN] = 1 or CONTROL2[SEND_HW_RESET] = 1 to instruct the neighboring device to issue the corresponding tone to the problem device. The detection of the tone is supported from the COMH and COML ports on stack devices regardless of the [DIR_SEL] setting. This does not apply to a base device because a base device detects pings instead.
Ping/Tone | Propagable | Non-Propagable |
---|---|---|
WAKE | Receiving device will generate a WAKE tone to the next device | |
SLEEPtoACTIVE | Receiving device will generate a SLEEPtoACTIVE tone to the next device | |
SHUTDOWN | Receiving device will initialize the shutdown process | |
HW_RESET | Receiving device will initialize the HW reset process |