CSR 8645 Module SPI Pinout - Page 1
Forum section: electronics / projects

author: JamesDean59
author_rank: Newbie
timestamp: July 28, 2021, 05:31:33 am
content: Good Morning!I'm trying to reprogram some CSR 8645 bluetooth modules I purchased from China. These modules appear to be different than just about every other I've come across. They have a different pin out. They have a different layout.I've got all the CSR software downloaded and installed. I've got the CSR USB->SPI adapter as well. I was able to communicate with a different CSR chip a while back so I am pretty sure this module's pin out is different from everything I've seen online.Has anyone seen this module before? I've not had any luck finding any useful information. Just about every picture/website I've seen is the one on the left in my attachment.Thanks!--Kris

author: Buriedcode
author_rank: Super Contributor
timestamp: July 30, 2021, 10:34:50 pm
content: Can't say I've seen that particular module, but it looks like its already on a board - does the board have any test pads for some pins? Sometimes they break these out for pogo pins so they can add a custom name for the device.Edit: if you look on the right picture, it looks like there are 4 caps on those pins labelled as speaker outputs in your left picture, so I don't think it was unreasonable to assume they have the same pinout. The SPI_EN pin siwtches the SPI port from I2S mode to SPI, so if the PCB is driving this pin already you can't use SPI.A larger photo of the whole carrier PCB woudl help

author: JamesDean59
author_rank: Newbie
timestamp: July 31, 2021, 02:41:16 am
content: I've attached a pic of the full board assembly.Assuming the pin outs are the same I don't see any connection to the SPI_EN pin. There is no pad underneath. I also dont see any pads that might have been used for pogo. I've always wanted a schematic for this assembly but I've never been able to find one. Any vendor I ask claims to have none.

author: Buriedcode
author_rank: Super Contributor
timestamp: July 31, 2021, 10:34:48 pm
content: Another observation, that thick trace on the left (7th pin frm the bottom left, going up). According to the "standard" module (I guess thats what we'll call it, since its the same as the ones I have here, the F-3188) thats "Rx" which wouldn't be such a large trace, and certainly wouldn't go to multiple resistors. Is that soldered to the board? and if so, I'm guessing thats the Vbat pin, powered by the LM317 on board. That pretty much confirms what you said, this isn't the same pinout. But the fact that it seems the speaker and mic connections are in the same area, along with the button IO (bottom left), means it probably isn't radically different.Figuring out the pinout won't be easy, but there are some clues. The IO voltage is based off the internal 1.8V reg, so when powered up, outputs will be either 0 or 1.8V, with enough current to drive an LED. Inputs can have weak pull downs that I believe are always enabled on the 8645.Another clue might come from the pin behavior on power up. That is, hooking up the unknown pins on the left to a logic analyzer, and powering up the board.I just tried to find that board on google. I could only find ones using the CSRA64215.. but the pinout on the modules on the board, appear to have the same pins soldered. Are these boards working? Because the CSRA64215 pinout is completely different, and looking at your board, makes sense.Example:https://www.thanksbuyer.com/bluetooth-receiver-board-module-lossless-bluetooth-5-0-receiver-qcc3008-b-type-w-external-antenna-kit-67653Looks like the same pins are soldered on that as yours, but the module used has a completely different pinout:https://www.aliexpress.com/item/32819647079.htmlBut I agree your module is definately note the same as the standard F3188. Perhaps they made a 8645 module, with the same pinout as the CSRA64215?

author: scottmarley
author_rank: Newbie
timestamp: April 14, 2024, 03:41:21 pm
content: For anyone else looking at this thread in the future, @Buriedcode is correct, this is a CSR 8645 chip with the same pinout as the CSR A64215 module. I have the same board as the OP and have hooked it up as shown in this video:.The name can then be easily changed using PSTools as usual.