# WP7607 SDIO voltage levels **URL:** \ **Category:** Uncategorized\ **Created:** [May 22, 2020, 9:52pm UTC](https://forum.legato.io/t/wp7607-sdio-voltage-levels/5206 "2020-05-22T21:52:36Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![Ymark](https://avatars.discourse-cdn.com/v4/letter/y/0ea827/32.png) [@Ymark](https://forum.legato.io/u/Ymark)\ **Post date:** [May 22, 2020, 9:52pm UTC](https://forum.legato.io/t/wp7607-sdio-voltage-levels/5206/1 "2020-05-22T21:52:36Z")
The SDIO data lines voltage is specified in the datasheet to have two levels 1.8V/2.85V Is there a way to tell the WP7607 to use SDIO data signals at 1.8V and if yes how? ---
**Author:** ![jyijyi](https://sea1.discourse-cdn.com/flex019/user_avatar/forum.legato.io/jyijyi/32/822_2.png) [@jyijyi](https://forum.legato.io/u/jyijyi)\ **Post date:** [May 23, 2020, 4:06am UTC](https://forum.legato.io/t/wp7607-sdio-voltage-levels/5206/2 "2020-05-23T04:06:33Z")
Seems this is controlled by protocol negotiation. I saw the folowing in yocto source about mmc card which seems can set the voltage, you can give a try: /kernel/driver/mmc/core/core.c, in function mmc\_power\_up(), mmc\_set\_ios(host); /\* Try to set signal voltage to 3.3V but fall back to 1.8v or 1.2v \*/ // if (\_\_mmc\_set\_signal\_voltage(host, MMC\_SIGNAL\_VOLTAGE\_330) == 0) // dev\_dbg(mmc\_dev(host), “Initial signal voltage of 3.3v\n”); // else if (\_\_mmc\_set\_signal\_voltage(host, MMC\_SIGNAL\_VOLTAGE\_180) == 0) if (\_\_mmc\_set\_signal\_voltage(host, MMC\_SIGNAL\_VOLTAGE\_180) == 0) dev\_dbg(mmc\_dev(host), “Initial signal voltage of 1.8v\n”); else if (\_\_mmc\_set\_signal\_voltage(host, MMC\_SIGNAL\_VOLTAGE\_120) == 0) dev\_dbg(mmc\_dev(host), “Initial signal voltage of 1.2v\n”); ---
**Author:** ![Ymark](https://avatars.discourse-cdn.com/v4/letter/y/0ea827/32.png) [@Ymark](https://forum.legato.io/u/Ymark)\ **Post date:** [May 30, 2020, 8:46am UTC](https://forum.legato.io/t/wp7607-sdio-voltage-levels/5206/3 "2020-05-30T08:46:52Z")
Thanks for the info, this solved part of the problem Our application is battery operated and as such the Wi-Fi module is switched off until it is needed We see that on power up the WP7607 tries to access the SDIO bus in 1.8V and then in 2.85V and then it decides that there is no SDIO user. 1 - is it possible to stop the WP7607 from searching SDIO device on power up? 2 - is there a HW siganl that the WP7607 is checking to decide if to start negotiations on the SDIO bus? 3 - How to restart the SDIO bus negotiation on demand (after Wi-Fi module power up) and to ensure it does the negotiations only at 1.8V? 4 - is there a special procedure to do before disconnecting the communication with the Wi-Fi module so it can be switched off? 5 - Is it possible to save last session parameters in order to reestablish connection with the Wi-Fi module faster next time the Wi-Fi module is powered? Thanks, ---
**Author:** ![jyijyi](https://sea1.discourse-cdn.com/flex019/user_avatar/forum.legato.io/jyijyi/32/822_2.png) [@jyijyi](https://forum.legato.io/u/jyijyi)\ **Post date:** [May 30, 2020, 9:41am UTC](https://forum.legato.io/t/wp7607-sdio-voltage-levels/5206/4 "2020-05-30T09:41:33Z")
1. Have you tried the sd card detect pin? 2. Better consult the wifi vendor ---
**Author:** ![Ymark](https://avatars.discourse-cdn.com/v4/letter/y/0ea827/32.png) [@Ymark](https://forum.legato.io/u/Ymark)\ **Post date:** [May 30, 2020, 10:10am UTC](https://forum.legato.io/t/wp7607-sdio-voltage-levels/5206/5 "2020-05-30T10:10:32Z")
Thanks for the prompt response Please answer on points 1, 4 & 5 point 3 - I found a possible answer in StackExchange Linux forum, I’ll try it Thanks, ---
**Author:** ![jyijyi](https://sea1.discourse-cdn.com/flex019/user_avatar/forum.legato.io/jyijyi/32/822_2.png) [@jyijyi](https://forum.legato.io/u/jyijyi)\ **Post date:** [May 30, 2020, 12:24pm UTC](https://forum.legato.io/t/wp7607-sdio-voltage-levels/5206/6 "2020-05-30T12:24:38Z")
4.5 Better consult the wifi vendor 1. If i remember correctly, the default voltage for sd is 3V ---
**Author:** ![jyijyi](https://sea1.discourse-cdn.com/flex019/user_avatar/forum.legato.io/jyijyi/32/822_2.png) [@jyijyi](https://forum.legato.io/u/jyijyi)\ **Post date:** [June 1, 2020, 12:05am UTC](https://forum.legato.io/t/wp7607-sdio-voltage-levels/5206/7 "2020-06-01T00:05:39Z")
1. Another method is to use level shifter, you can refer to the mangoh schematic ---
**Author:** ![Ymark](https://avatars.discourse-cdn.com/v4/letter/y/0ea827/32.png) [@Ymark](https://forum.legato.io/u/Ymark)\ **Post date:** [June 1, 2020, 1:42pm UTC](https://forum.legato.io/t/wp7607-sdio-voltage-levels/5206/8 "2020-06-01T13:42:50Z")
Thanks, We managed to make the WP7607 work only at 1.8V SDIO signal levels ---
**Author:** ![jyijyi](https://sea1.discourse-cdn.com/flex019/user_avatar/forum.legato.io/jyijyi/32/822_2.png) [@jyijyi](https://forum.legato.io/u/jyijyi)\ **Post date:** [June 1, 2020, 2:14pm UTC](https://forum.legato.io/t/wp7607-sdio-voltage-levels/5206/9 "2020-06-01T14:14:18Z")
Do you use level shifter? ---
**Author:** ![Ymark](https://avatars.discourse-cdn.com/v4/letter/y/0ea827/32.png) [@Ymark](https://forum.legato.io/u/Ymark)\ **Post date:** [June 1, 2020, 2:26pm UTC](https://forum.legato.io/t/wp7607-sdio-voltage-levels/5206/10 "2020-06-01T14:26:19Z")
No, we managed to find the place in the SDIO driver and modify it to work only at 1.8V ---
**Author:** ![tjayaprakash](https://avatars.discourse-cdn.com/v4/letter/t/958977/32.png) [@tjayaprakash](https://forum.legato.io/u/tjayaprakash)\ **Post date:** [August 12, 2020, 9:47am UTC](https://forum.legato.io/t/wp7607-sdio-voltage-levels/5206/11 "2020-08-12T09:47:24Z")
Hi Ymark, Can you let us know where in the SDIO driver the value of 3V was changed to 1.8V. Currently, we have a custom board, where we r using WP7606 and Talon Wifi wl18xx module connected to SDIO lines. As in the MangoH red board, we do not have a level translator to 3V. Your solution might help in getting this working. ---
**Author:** ![TalonCom](https://sea1.discourse-cdn.com/flex019/user_avatar/forum.legato.io/taloncom/32/997_2.png) [@TalonCom](https://forum.legato.io/u/TalonCom)\ **Post date:** [August 25, 2020, 5:20pm UTC](https://forum.legato.io/t/wp7607-sdio-voltage-levels/5206/12 "2020-08-25T17:20:08Z")
The Mirage WiFi WL18 card uses 1.8v for all interface lines. ---
**Author:** ![Ymark](https://avatars.discourse-cdn.com/v4/letter/y/0ea827/32.png) [@Ymark](https://forum.legato.io/u/Ymark)\ **Post date:** [September 6, 2020, 3:31pm UTC](https://forum.legato.io/t/wp7607-sdio-voltage-levels/5206/13 "2020-09-06T15:31:41Z")
Hi, Below is the code I received from our software engineer Hope this will help you BR Yehuda diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c index 367f3b225f11…ed81829ce685 100644 — a/drivers/mmc/core/core.c +++ b/drivers/mmc/core/core.c @@ -2699,11 +2699,11 @@ void mmc\_power\_up(struct mmc\_host \*host, u32 ocr) host-\>ios.timing = MMC\_TIMING\_LEGACY; mmc\_set\_ios(host); - ``` /* Try to set signal voltage to 3.3V but fall back to 1.8v or 1.2v */ ``` - ``` if (__mmc_set_signal_voltage(host, MMC_SIGNAL_VOLTAGE_330) == 0) ``` - ``` /* Try to set signal voltage to 1.8V but fall back to 3.3v or 1.2v */ ``` - ``` if (__mmc_set_signal_voltage(host, MMC_SIGNAL_VOLTAGE_180) == 0) ``` - ``` dev_dbg(mmc_dev(host), "Initial signal voltage of 1.8v\n"); ``` - ``` else if (__mmc_set_signal_voltage(host, MMC_SIGNAL_VOLTAGE_330) == 0) dev_dbg(mmc_dev(host), "Initial signal voltage of 3.3v\n"); ``` - ``` else if (__mmc_set_signal_voltage(host, MMC_SIGNAL_VOLTAGE_180) == 0) ``` - ``` dev_dbg(mmc_dev(host), "Initial signal voltage of 1.8v\n"); else if (__mmc_set_signal_voltage(host, MMC_SIGNAL_VOLTAGE_120) == 0) dev_dbg(mmc_dev(host), "Initial signal voltage of 1.2v\n"); ```