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| author | Vincent Palatin <vpalatin@chromium.org> | 2013-06-10 17:43:42 -0700 |
|---|---|---|
| committer | ChromeBot <chrome-bot@google.com> | 2013-06-11 10:19:48 -0700 |
| commit | 71612e73d7718338d0479f4e9546467e801b51fc (patch) | |
| tree | 1b31b9ccc77f18b8218f04c07faede463f94525d | |
| parent | 6fdd37c71becdad402a2368ec3b22c6dab2e6b35 (diff) | |
| download | chrome-ec-71612e73d7718338d0479f4e9546467e801b51fc.tar.gz | |
spring: update PWM characterization for DVT1
The new constants used to convert PWM duty cycle to input current,
based on a linear regression done on Aaron's characterization data
measured on DVT1 PCB.
The data points are linear enough to use the linear relationship
to set the current limitation.
Signed-off-by: Vincent Palatin <vpalatin@chromium.org>
BRANCH=spring
BUG=chrome-os-partner:19281
TEST=none
Original-Change-Id: I8378aaea21d5b3229d505caf4849257ded77e1ad
Reviewed-on: https://gerrit.chromium.org/gerrit/58143
Reviewed-by: Vic Yang <victoryang@chromium.org>
Commit-Queue: Vincent Palatin <vpalatin@chromium.org>
Tested-by: Vincent Palatin <vpalatin@chromium.org>
(cherry picked from commit d7b9b2a088dcf129739c7a6b8a30bc292ea7234d)
Change-Id: I11962991d6d7ba7b9d437fc56eb23974d30930a8
Reviewed-on: https://gerrit.chromium.org/gerrit/58198
Commit-Queue: Vincent Palatin <vpalatin@chromium.org>
Tested-by: Vincent Palatin <vpalatin@chromium.org>
Reviewed-by: Vic Yang <victoryang@chromium.org>
| -rw-r--r-- | common/extpower_usb.c | 27 |
1 files changed, 15 insertions, 12 deletions
diff --git a/common/extpower_usb.c b/common/extpower_usb.c index 7fdff81fa2..17ad401001 100644 --- a/common/extpower_usb.c +++ b/common/extpower_usb.c @@ -48,12 +48,22 @@ enum ilim_config { /* Voltage threshold of D+ for video */ #define VIDEO_ID_THRESHOLD 1335 +/* + * Mapping from PWM duty to current: + * Current = A + B * PWM_Duty + */ +#define PWM_MAPPING_A 2958 +#define PWM_MAPPING_B (-29) + +/* Map current in milli-amps to PWM duty cycle percentage */ +#define MA_TO_PWM(curr) (((curr) - PWM_MAPPING_A) / PWM_MAPPING_B) + /* PWM controlled current limit */ -#define I_LIMIT_500MA 90 -#define I_LIMIT_1000MA 75 -#define I_LIMIT_1500MA 60 -#define I_LIMIT_2000MA 50 -#define I_LIMIT_2400MA 35 +#define I_LIMIT_500MA MA_TO_PWM(500) +#define I_LIMIT_1000MA MA_TO_PWM(1000) +#define I_LIMIT_1500MA MA_TO_PWM(1500) +#define I_LIMIT_2000MA MA_TO_PWM(2000) +#define I_LIMIT_2400MA MA_TO_PWM(2400) #define I_LIMIT_3000MA 0 /* PWM control loop parameters */ @@ -76,13 +86,6 @@ enum ilim_config { #define DELAY_USB_DP_DN_MS 20 #define DELAY_ID_MUX_MS 30 -/* - * Mapping from PWM duty to current: - * Current = A + B * PWM_Duty - */ -#define PWM_MAPPING_A 3012 -#define PWM_MAPPING_B (-29) - /* Current sense resistor values */ #define R_INPUT_MOHM 20 /* mOhm */ #define R_BATTERY_MOHM 33 /* mOhm */ |