> For the complete documentation index, see [llms.txt](https://docs.kpk.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.kpk.io/funds/infrastructure/onchain-accounting/price-feeds/syrupusdc.md).

# syrupUSDC

Custom price feed for **Maple Finance syrupUSDC** on Ethereum mainnet. syrupUSDC is an ERC-4626 vault share representing a deposit in Maple's USDC lending pool. The price is derived from the vault's current share-to-USDC conversion rate multiplied by the USDC/USD price read from the NAV's own primary feed.

**Source:** [`syrupUSDC_CustomPriceFeed.sol`](https://github.com/karpatkey/onchain-accounting/blob/main/src/prices/protocols/syrupUSDC_CustomPriceFeed.sol)

{% hint style="info" %}
**Mainnet feed.** The L2 deployments use a different oracle composition — see [syrupUSDC (L2)](/funds/infrastructure/onchain-accounting/price-feeds/syrupusdc-l2.md).
{% endhint %}

{% hint style="info" %}
The USDC/USD term is sourced from the NAV's own selector — see [Base/USD from the NAV's own selector](/funds/infrastructure/onchain-accounting/price-feeds.md#base-usd-from-the-navs-own-selector).
{% endhint %}

***

## Approach

`syrupUSDC.convertToAssets(1 syrupUSDC)` × USDC/USD (from the NAV's primary feed via `getPriceDataNoDivergence(USDC)`)

<figure><img src="/files/RjOp3lGTsHDLnAqVFpTT" alt="Left-to-right flowchart of the syrupUSDC (Mainnet) price feed: rate and Chainlink inputs combine into a USD price, with a staleness gate."><figcaption><p>syrupUSDC (Mainnet) price feed — how its oracle inputs compose into a USD price, with the staleness gate.</p></figcaption></figure>

***

## Price calculation

```
decimals = syrupUSDC.decimals()                       // vault share decimals
rate     = syrupUSDC.convertToAssets(10^decimals)     // USDC per 1 syrupUSDC (vault decimals)
price    = rate × USDC_USD / 10^decimals
```

| Input               | Source                                              | Description                                                     |
| ------------------- | --------------------------------------------------- | --------------------------------------------------------------- |
| `convertToAssets()` | `IERC4626(syrupUSDC)`                               | USDC backing per 1 syrupUSDC at the current vault exchange rate |
| `USDC_USD`          | NAV base — `getPriceDataNoDivergence(USDC)` (8 dec) | the NAV's primary USDC/USD price                                |

Vault decimals are read once at deploy. Result carries the feed's **8 decimals**.

***

## Constructor

```solidity
constructor(
    address syrupUsdc_,
    address nav_,
    address baseAsset_
)
```

| Parameter    | Description                                                                                                                                 |
| ------------ | ------------------------------------------------------------------------------------------------------------------------------------------- |
| `syrupUsdc_` | The syrupUSDC vault address (also used to read vault decimals)                                                                              |
| `nav_`       | NAVCalculator (proxy) — supplies the base stablecoin's USD price via `getPriceDataNoDivergence`                                             |
| `baseAsset_` | The registered base stablecoin whose USD price is read (USDC); **must equal the vault's `asset()`** — reverts `BaseAssetMismatch` otherwise |

***

## Staleness

The price is stale if the base USD price is `≤ 0`, or if the NAV reports the base asset (USDC) stale — all its feeds stale. The base leg's `updatedAt` comes from the NAV's selected USDC feed. The `convertToAssets` rate has no heartbeat — it is a live view on the ERC-4626 vault.

***

## Chains

Deployed on **Ethereum mainnet** only. L2 deployments use [syrupUSDC (L2)](/funds/infrastructure/onchain-accounting/price-feeds/syrupusdc-l2.md), which relies on a Chainlink syrupUSDC/USDC feed instead.


---

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