Wireless power systems with frequency-shift-keying communications
A wireless power system has a wireless power transmitting device and a wireless power receiving device. The devices in the wireless power system may communicate using in-band communication. The wireless power transmitting device may transmit data to the wireless power receiving device using frequency-shift keying (FSK) modulation. The receiving device may not be aware of the transmission rate of the FSK data. The FSK decoder may identify an actual transmission rate of the incoming bits and decode the wireless power signals into subsequent bits using the actual transmission rate.
1. An electronic device comprising:
wireless power transmission circuitry having a coil operable to transfer wireless power signals with an additional wireless charging device at a wireless power transfer frequency; and
a frequency-shift keying decoder operable to decode data received from the additional wireless charging device during wireless power transmission, wherein:
the data is represented using frequency-shift keying characteristics encoded into to the wireless power signal by the additional wireless charging device;
the data is encoded at an actual transmission rate, selected by the additional wireless charging device, amongst a plurality of permitted transmission rates, wherein the permitted transmission rates are data transmission rates that are possible for transferring data while transferring wireless power signals at the wireless power transfer frequency; and
the frequency-shift keying decoder is configured to identify the actual transmission rate using information in the encoded data.
2. The electronic device of claim 1 , wherein the frequency-shift keying decoder comprises multiple channels each operating at a respective fixed transmission rate.
3. The electronic device of claim 1 , wherein the frequency-shift keying decoder comprises a single decoder channel that operates at different transmission rates at different times.
4. The electronic device of claim 1 , wherein the frequency-shift keying decoder is configured to, using a first decoder channel:
decode the data at a first transmission rate;
compare the data decoded at the first transmission rate against a checksum; and
output the data decoded at the first transmission rate if the checksum is valid.
5. The electronic device of claim 4 , wherein the frequency-shift keying decoder is configured to discard the data decoded at the first transmission rate if the checksum is invalid.
6. The electronic device of claim 4 , wherein the frequency-shift keying decoder is configured to, using the first decoder channel and if the checksum is invalid:
decode the data at a second transmission rate;
compare the data decoded at the second transmission rate against an additional checksum; and
output the data decoded at the second transmission rate if the additional checksum is valid.
7. The electronic device of claim 4 , wherein the frequency-shift keying decoder is configured to, using a second decoder channel:
decode the data at a second transmission rate;
compare the data decoded at the second transmission rate against an additional checksum; and
output the data decoded at the second transmission rate if the additional checksum is valid.
8. The electronic device of claim 1 , wherein the frequency-shift keying decoder is configured to:
periodically scan a decoder channel for a predetermined preamble at a first transmission rate; and
in accordance with identifying the predetermined preamble in the data, decode subsequently received data using the first transmission rate.
9. The electronic device of claim 8 , wherein the frequency-shift keying decoder is configured to:
periodically scan the decoder channel for the predetermined preamble at a second transmission rate that is different than the first transmission rate.
10. The electronic device of claim 8 , wherein the predetermined preamble is known by the electronic device and the additional wireless charging device before data transmission commences.
11. The electronic device of claim 8 , wherein the predetermined preamble is a series of same bits.
12. The electronic device of claim 8 , wherein the predetermined preamble is a series of 1 bits.
13. The electronic device of claim 8 , wherein the predetermined preamble is a series of 0 bits.
14. A method of operating an electronic device comprising wireless power transmission circuitry having a coil and a frequency-shift keying decoder, the method comprising:
using the coil, transferring wireless power signals with an additional wireless charging device at a wireless power transfer frequency; and
using the frequency-shift keying decoder:
decoding data received from the additional wireless charging device during wireless power transmission, wherein:
the data is represented using frequency-shift keying characteristics encoded into to the wireless power signal by the additional wireless charging device; and
the data is encoded at an actual transmission rate, selected by the additional wireless charging device, amongst a plurality of permitted transmission rates, wherein the permitted transmission rates are data transmission rates that are possible for transferring data while transferring wireless power signals at the wireless power transfer frequency; and
identifying the actual transmission rate using information in the encoded data.
15. The method of claim 14 , further comprising:
using a first decoder channel in the frequency-shift keying decoder:
decoding the data at a first transmission rate;
comparing the data decoded at the first transmission rate against a checksum; and
outputting the data decoded at the first transmission rate if the checksum is valid.
16. The method of claim 14 , further comprising:
using the frequency-shift keying decoder:
periodically scanning a decoder channel for a predetermined preamble at a first transmission rate; and
in accordance with identifying the predetermined preamble in the data, decoding subsequently received data using the first transmission rate.
17. The method of claim 16 , wherein the predetermined preamble is a series of same bits.
18. A method of operating a frequency-shift keying decoder in an electronic device, the method comprising:
decoding data received from an additional wireless charging device during wireless power transmission at a wireless power transfer frequency, wherein:
the data is represented using frequency-shift keying characteristics encoded into a wireless power signal by the additional wireless charging device; and
the data is encoded at an actual transmission rate, selected by the additional wireless charging device, amongst a plurality of permitted transmission rates, wherein the permitted transmission rates are data transmission rates that are possible for transferring data while transferring wireless power signals at the wireless power transfer frequency; and
identifying the actual transmission rate using information in the encoded data.
19. The method of claim 18 , further comprising:
using a first decoder channel in the frequency-shift keying decoder:
decoding the data at a first transmission rate;
comparing the data decoded at the first transmission rate against a checksum; and
outputting the data decoded at the first transmission rate if the checksum is valid.
20. The method of claim 18 , further comprising:
periodically scanning a decoder channel for a predetermined preamble at a first transmission rate; and
in accordance with identifying the predetermined preamble in the data, decoding subsequently received data using the first transmission rate.